month comparative periods, net interest margin decreased quarter-over-quarter primarily due to a decrease in rates earned, while net interest margin remained consistent for the six months ended June 30, 2021 compared to the six months ended June 30, 2020 primarily due to $2.0 million in PPP income earned in 2021 compared to $0.4 million in 2020.
Average interest-earning assets increased $87.1 million, or 5.5%, to $1.66 billion for the quarter ended June 30, 2021 compared to $1.57 billion for the quarter ended June 30, 2020, and average interest bearing liabilities decreased $17.7 million, or 1.5%, to $1.14 billion for the quarter ended June 30, 2021 compared to $1.16 billion for the quarter ended June 30, 2020.
Average interest-earning assets increased $152.1 million, or 10.1%, to $1.66 billion for the six months ended June 30, 2021 compared to $1.50 billion for the six months ended June 30, 2020, average interest bearing liabilities increased $20.9 million, or 1.8%, to $1.16 billion for the six months ended June 30, 2021 compared to $1.14 billion for the six months ended June 30, 2020.
Total interest income (expressed on a fully taxable equivalent basis) was $15.6 million and $32.0 million for the three and six months ended June 30, 2021, respectively, compared to $15.9 million and $31.9 million for the three and six months ended June 30, 2020, respectively. The Company’s rates earned on interest earning assets were 3.77% and 3.90% for the three and six months ended June 30, 2021, respectively, compared to 4.07% and 4.26% for the three and six months ended June 30, 2020, respectively.
Interest income on loans held for investment was $14.0 million and $29.2 million for the three and six months ended June 30, 2021, respectively, compared to $14.6 million and $29.1 million for the three and six months ended June 30, 2020, respectively.
Average loans outstanding increased $19.0 million, or 1.5%, to $1.28 billion for the quarter ended June 30, 2021 compared to $1.26 billion for the quarter ended June 30, 2020. The average yield on loans decreased to 4.42% for the quarter ended June 30, 2021 compared to 4.68% for the quarter ended June 30, 2020.
Average loans outstanding increased $66.6 million, or 5.5%, to $1.28 billion for the six months ended June 30, 2021 compared to $1.21 billion for the six months ended June 30, 2020. The average yield on loans decreased to 4.61% for the six months ended June 30, 2021 compared to 4.84% for the six months ended June 30, 2020. See the Lending and Credit Management section for further discussion of changes in the composition of the lending portfolio.
Interest income on available-for-sale securities was $1.4 million and $2.4 million for the three and six months ended June 30, 2021, respectively, compared to $1.1 million and $2.1 million for the three and six months ended June 30, 2020, respectively.
Average securities increased $59.7 million, or 30.1%, to $257.9 million for the quarter ended June 30, 2021 compared to $198.3 million for the quarter ended June 30, 2020. The average yield on securities decreased to 2.10% for the quarter ended June 30, 2021 compared to 2.15% for the quarter ended June 30, 2020.
Average securities increased $46.2 million, or 24.3%, to $236.9 million for the six months ended June 30, 2021 compared to $190.7 million for the six months ended June 30, 2020. The average yield on securities decreased to 2.08% for the six months ended June 30, 2021 compared to 2.23% for the six months ended June 30, 2020. Management plans to continue to grow the investment portfolio based on available liquidity. See the Liquidity Management section for further discussion.
Total interest expense decreased to $1.5 million and $3.2 million for the three and six months ended June 30, 2021, respectively, compared to $2.4 million and $5.7 million for the three and six months ended June 30, 2020, respectively. The Company’s rates paid on interest bearing liabilities were 0.53% and 0.56% for the three and six months ended June 30, 2021, respectively, compared to 0.82% and 1.0% for the three and six months ended June 30, 2020, respectively. See the Liquidity Management section for further discussion.