SUMMARY PROSPECTUS
February 28, 2013
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MFS
®
Inflation-Adjusted Bond Fund
Before you invest
, you may want to review the funds prospectus, which contains more information about the fund and its risks. You can find the funds prospectus and other information about the fund, including the funds statement of additional information, online at funds.mfs.com. You can also get this information at no cost by calling 1-800-225-2606 or by sending an e-mail request to orderliterature@mfs.com. The funds prospectus and statement of additional information, both dated February 28, 2013, as may be supplemented from time to time, are incorporated by reference into this Summary Prospectus.
CLASS
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TICKER
SYMBOL
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Class A
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MIAAX
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Class B
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MIABX
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Class C
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MIACX
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Class I
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MIAIX
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Class R1
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MIALX
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Class R2
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MIATX
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Class R3
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MIAHX
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Class R4
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MIAJX
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Class R5
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MIAKX
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Summary of Key Information
Investment Objective
The funds investment objective is to seek total return that exceeds the rate of inflation over the long-term, with an emphasis on current income, but also considering capital appreciation.
Fees and Expenses
This table describes the fees and expenses that you may pay when you buy and hold shares of the fund. Expenses for Class A, Class B, Class C, Class I, Class R1, Class R2, Class R3, and Class R4 shares have been adjusted to reflect current fee arrangements. The annual fund operating expenses for Class R5 shares are based on estimated Other Expenses for the current fiscal year expressed as a percentage of the funds estimated average net assets during the period.
You may qualify for sales charge reductions if you and certain members of your family invest, or agree to invest in the future, at least $50,000 in MFS Funds. More information about these and other waivers and reductions is available from your financial intermediary and in Sales Charges and Waivers or Reductions on page 8 of the funds prospectus and Waivers of Sales Charges on page I-15 of the funds statement of additional information Part I.
Shareholder Fees (fees paid directly from your investment):
Share Class
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A
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B
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C
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I
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ALL R
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Maximum Sales Charge
(Load) Imposed on Purchases (as a percentage of offering price)
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4.75
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%
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None
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None
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None
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None
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Maximum Deferred Sales Charge
(Load) (as a percentage of original purchase price or redemption proceeds, whichever is less)
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1.00
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%
#
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4.00
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%
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1.00
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%
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None
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None
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Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):
Share Class
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A
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B
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C
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I
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R1
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R2
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R3
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R4
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R5
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Management Fee
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0.50
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%
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0.50
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%
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0.50
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%
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0.50
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%
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0.50
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%
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0.50
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%
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0.50
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%
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0.50
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%
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0.50
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%
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Distribution and/or Service (12b-1) Fees
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0.25
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%
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1.00
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%
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1.00
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%
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None
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1.00
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%
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0.50
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%
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0.25
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%
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None
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None
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Other Expenses
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0.25
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%
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0.25
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%
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0.25
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%
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0.25
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%
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0.25
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%
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0.25
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%
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0.25
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%
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0.25
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%
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0.18
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%
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Total Annual Fund Operating Expenses
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1.00
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%
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1.75
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%
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1.75
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%
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0.75
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%
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1.75
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%
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1.25
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%
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1.00
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%
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0.75
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%
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0.68
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%
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Fee Reductions and/or Expense Reimbursements
1
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(0.20
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)%
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(0.20
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)%
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(0.10
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)%
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(0.10
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)%
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(0.10
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)%
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(0.10
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)%
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(0.10
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)%
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(0.10
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)%
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(0.08
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)%
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Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements
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0.80
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%
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1.55
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%
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1.65
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%
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0.65
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%
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1.65
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%
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1.15
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%
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0.90
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%
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0.65
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%
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0.60
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%
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#
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On shares purchased without an initial sales charge and redeemed within 18 months of purchase for shares purchased on or after August 1, 2012, and within 24 months of purchase for shares purchased prior to August 1, 2012.
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1
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MFS Fund Distributors, Inc., has agreed in writing to waive the Class A service fee to 0.15% of the funds average daily net assets annually until modified by the funds Board of Trustees, but such agreement will continue until at least February 28, 2014. In addition, assets attributable to Class B shares purchased prior to May 1, 2006 are subject to the Class B service fee of 0.25% of the funds average daily net assets annually. On assets attributable to all other Class B shares, MFS Fund Distributors, Inc., has agreed in writing to waive the Class B service fee to 0.15% of the funds average daily net assets annually until modified by the funds Board of Trustees, but such agreement will continue until at least February 28, 2014. In addition, Massachusetts Financial Services Company has agreed in writing to bear the funds expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses (such as interest and borrowing expenses incurred in connection with the funds investment activity), such that Total Annual Fund Operating Expenses do not exceed 0.80% of the funds average daily net assets annually for Class A shares, 1.55% of the funds average daily net assets annually for Class B shares, 1.65% of the funds average daily net assets annually for each of Class C and Class R1 shares, 0.65% of the funds average daily net assets annually for each of Class I and Class R4 shares, 1.15% of the funds average daily net assets annually for Class R2 shares, 0.90% of the funds average daily net assets annually for Class R3 shares, and 0.60% of the funds average daily net assets annually for Class R5 shares. This written agreement will continue until modified by the funds Board of Trustees, but such agreement will continue until at least February 28, 2014.
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IAB-SUM-022813
Page 1 of 4
MFS Inflation-Adjusted Bond Fund
Example
This example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds.
The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods (unless otherwise indicated); your investment has a 5% return each year; and the funds operating expenses remain the same.
Although your actual costs will likely be higher or lower, under these assumptions your costs would be:
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1 YEAR
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3 YEARS
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5 YEARS
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10 YEARS
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Class A
Shares
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$
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553
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$
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759
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$
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983
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$
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1,624
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Class B
Shares assuming
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redemption at end of period
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$
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558
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$
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832
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$
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1,130
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$
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1,847
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no redemption at end of period
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$
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158
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$
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532
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$
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930
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$
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1,847
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Class C
Shares assuming
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redemption at end of period
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$
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268
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$
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541
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$
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940
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$
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2,054
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no redemption at end of period
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$
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168
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$
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541
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$
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940
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$
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2,054
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Class I
Shares
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$
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66
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$
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230
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$
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407
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$
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921
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Class R1
Shares
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$
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168
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$
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541
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$
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940
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$
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2,054
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|
Class R2
Shares
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$
|
117
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|
$
|
387
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$
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677
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$
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1,503
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Class R3
Shares
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$
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92
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$
|
308
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$
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543
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$
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1,216
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Class R4
Shares
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$
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66
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$
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230
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$
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407
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$
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921
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|
Class R5
Shares
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$
|
61
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$
|
210
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$
|
371
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$
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839
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|
Portfolio Turnover
The fund pays transaction costs, such as commissions, when it buys and sells securities (or turns over its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These transaction costs, which are not reflected in Annual Fund Operating Expenses or in the Example, affect the funds performance. During the most recent fiscal year, the funds portfolio turnover rate was 26% of the average value of its portfolio.
Principal Investment Strategies
MFS (Massachusetts Financial Services Company, the funds investment adviser) normally invests at least 80% of the funds net assets in inflation-adjusted debt instruments and other investments with inflation-adjusting features.
MFS currently intends to focus the funds investments in inflation-adjusted debt instruments issued by the U.S. Treasury. MFS may also invest the funds assets in other inflation-adjusted debt instruments and non-inflation-adjusted debt instruments.
MFS generally invests substantially all of the funds assets in investment grade debt instruments.
MFS may invest a relatively large percentage of the funds assets in a single issuer or a small number of issuers.
MFS may invest the funds assets in foreign securities.
While MFS may use derivatives for any investment purpose, to the extent MFS uses derivatives, MFS expects to use derivatives primarily to increase or decrease exposure to a particular market, segment of the market, or security, to increase or decrease interest rate exposure, or as alternatives to direct investments. Derivatives include futures, forward contracts, options, structured securities, inverse floating rate instruments, and swaps.
MFS allocates the funds assets across maturities and types of debt instruments based on its evaluation of macroeconomic factors, including interest rates, inflation rates, and monetary and fiscal policies.
MFS uses a bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual instruments and their issuers. Quantitative models that systematically evaluate instruments may also be considered. In structuring the fund, MFS may also consider top-down factors.
Principal Risks
As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.
The principal risks of investing in the fund are:
Interest Rate Risk:
The price of a debt instrument falls when interest rates rise and rises when interest rates fall. Instruments with longer maturities, or that do not pay current interest, are more sensitive to interest rate changes.
Credit Risk:
The price of a debt instrument depends, in part, on the credit quality of the issuer, borrower, counterparty, or underlying collateral or assets and the terms of the instrument. The price of a debt instrument can decline in response to changes in the financial condition of the issuer, borrower, counterparty, or underlying collateral or assets, or changes in specific or general market, economic, industry, political, regulatory, geopolitical, and other conditions.
U.S. Government securities not supported as to the payment of principal or interest by the U.S. Treasury are subject to greater credit risk than are U.S. Government securities supported by the U.S. Treasury.
Issuer Focus Risk:
The funds performance could be more volatile than the performance of more diversified funds.
Foreign Risk:
Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, and other conditions. These factors can make foreign investments, especially those in emerging markets, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market.
Prepayment/Extension Risk:
Instruments subject to prepayment and/or extension can reduce the potential for gain for the instruments holders if the instrument is prepaid and increase the potential for loss if the maturity of the instrument is extended.
Inflation-Adjusted Debt Instruments Risk:
Interest payments on inflation-adjusted debt instruments can be unpredictable and vary based on the level of inflation. If inflation is negative, principal and income can both decline.
Derivatives Risk:
Derivatives can be highly volatile and involve risks in addition to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives can be substantially greater than the derivatives original cost. Derivatives can involve leverage.
Leveraging Risk:
Leverage involves investment exposure in an amount exceeding the initial investment. Leverage can cause increased volatility by magnifying gains or losses.
Investment Selection Risk:
MFS investment analysis and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests.
Page 2 of 4
MFS Inflation-Adjusted Bond Fund
Counterparty and Third Party Risk:
Transactions involving a counterparty or third party other than the issuer of the instrument are subject to the credit risk of the counterparty or third party, and to the counterpartys or third partys ability to perform in accordance with the terms of the transaction.
Liquidity Risk:
It may not be possible to sell certain investments, types of investments, and/or segments of the market at any particular time or at an acceptable price.
Performance Information
The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the funds performance over time and how the funds performance over time compares with that of a broad measure of market performance.
The funds past performance (before and after taxes) does not necessarily indicate how the fund will perform in the future. Updated performance is available online at
mfs.com
or by calling 1-800-225-2606.
Class A Bar Chart.
The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the funds shares. If these sales charges were included, they would reduce the returns shown.
During the period(s) shown in the bar chart, the highest quarterly return was 5.17% (for the calendar quarter ended March 31, 2008) and the lowest quarterly return was (3.43)% (for the calendar quarter ended September 30, 2008).
Performance Table.
Average Annual Total Returns
(for the Periods Ended December 31, 2012)
Share Class
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1 YEAR
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|
5 YEARS
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LIFE
INCEPTION 9-30-2003
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Returns Before Taxes
|
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|
|
|
|
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B Shares
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1.21
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%
|
4.87
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%
|
4.67
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%
|
C Shares
|
|
4.09
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%
|
5.11
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%
|
4.52
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%
|
I Shares
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|
6.24
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%
|
6.19
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%
|
5.57
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%
|
R1 Shares
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|
5.10
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%
|
5.12
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%
|
4.44
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%
|
R2 Shares
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5.67
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%
|
5.65
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%
|
4.95
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%
|
R3 Shares
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6.00
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%
|
5.91
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%
|
5.23
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%
|
R4 Shares
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|
6.15
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%
|
6.15
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%
|
5.51
|
%
|
R5 Shares
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|
6.24
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%
|
6.19
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%
|
5.57
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%
|
A Shares
|
|
0.97
|
%
|
4.97
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%
|
4.86
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%
|
Returns After Taxes on Distributions
|
|
|
|
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A Shares
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0.12
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%
|
3.76
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%
|
3.49
|
%
|
Returns After Taxes on Distributions and Sale of Fund Shares
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|
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A Shares
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0.72
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%
|
3.54
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%
|
3.34
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%
|
Index Comparison (Reflects no deduction for fees, expenses or taxes)
|
|
|
|
|
|
|
|
Barclays U.S. Treasury Inflation Protected Securities Index
|
|
6.98
|
%
|
7.04
|
%
|
6.51
|
%
|
Aft
er-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. The after-tax returns are shown for only one of the funds classes of shares, and after-tax returns for the funds other classes of shares will vary from the returns shown.
Investment Adviser
MFS serves as the investment adviser for the fund.
Portfolio Manager(s)
Portfolio Manager
|
|
Since
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Title
|
Erik S. Weisman
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|
2003
|
|
Investment Officer of MFS
|
Purchase and Sale of Fund Shares
You may purchase and redeem shares of the fund each day the New York Stock Exchange is open for trading. You may purchase or redeem shares either by having your financial intermediary process your purchase or redemption, or through MFS Service Center, Inc. (MFSC) by overnight mail (MFSC, c/o Boston Financial Data Services, 30 Dan Road, Canton, MA 02021-2809), by mail ([Fund Name], P.O. Box 55824, Boston, MA 02205-5824), by telephone (1-800-225-2606), or via the Internet at
mfs.com
(MFS Access).
The funds initial and subsequent investment minimums generally are as follows:
Class
|
|
Initial Minimum
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|
Subsequent Minimum
|
Class A, Class B, Class C
|
|
None
automatic investment plans and certain asset-based fee programs
$25
employer-sponsored retirement plans
$250
Traditional and Roth IRAs
$1,000
other accounts
|
|
$50
by check and non-systematic written exchange request, and via MFSC telephone representatives
None
other purchases
|
Class I, Class R1, Class R2, Class R3, Class R4, Class R5
|
|
None
|
|
None
|
Taxes
If your shares are held in a taxable account, the funds distributions are taxable to you, and will be taxed as ordinary income and/or capital gains.
Page 3 of 4