Operating income for the Other segment, exclusive of corporate and unallocated expenses, was $2.2 million for the three-months ended June 30, 2021, an increase of approximately $0.6 million, or 37.2% higher than operating income of $1.6 million for the three-months ended June 30, 2020.
Interest and Other (Expense) Income, net. Interest and other non-operating (expense) income, net, was $0.9 million for the three-months ended June 30, 2021, as compared to interest and other non-operating (expense) income, net, of ($1.8) million for the three-months ended June 30, 2020. Foreign currency transaction losses were $1.8 million and $1.5 million for the three-months ended June 30, 2021 and 2020, respectively. Interest income was $1.1 million and $0.9 million for the three-months ended June 30, 2021 and 2020, respectively.
Provision for Income Taxes. Provision for income taxes was $123.1 million for the three-months ended June 30, 2021, an increase of $29.0 million, or 30.8% higher than the provision for income taxes of $94.1 million for the three-months ended June 30, 2020. The effective combined federal, state and foreign tax rate increased to 23.4% from 23.2% for the three-months ended June 30, 2021 and 2020, respectively.
Net Income. Net income was $403.8 million for the three-months ended June 30, 2021, an increase of 92.4 million, or 29.7% higher than net income of $311.4 million for the three-months ended June 30, 2020. The increase in net income for the three-months ended June 30, 2021 was primarily due to the $177.4 million increase in gross profit for the three-months ended June 30, 2021, partially offset by the $58.7 million increase in operating expenses and the $29.0 million increase in the provision for incomes taxes.
Results of Operations for the Six-Months Ended June 30, 2021 Compared to the Six-Months Ended June 30, 2020.
Net Sales. Net sales were $2.71 billion for the six-months ended June 30, 2021, an increase of approximately $549.8 million, or 25.5% higher than net sales of $2.16 billion for the six-months ended June 30, 2020. Net changes in foreign currency exchange rates had a favorable impact on net sales of approximately $47.9 million for the six-months ended June 30, 2021.
Net sales for the Monster Energy® Drinks segment were $2.54 billion for the six-months ended June 30, 2021, an increase of approximately $517.2 million, or 25.6% higher than net sales of $2.02 billion for the six-months ended June 30, 2020. Net sales for the Monster Energy® Drinks segment increased primarily due to increased worldwide sales by volume of our Monster Energy® brand energy drinks as a result of increased consumer demand. Net changes in foreign currency exchange rates had a favorable impact on net sales for the Monster Energy® Drinks segment of approximately $44.8 million for the six-months ended June 30, 2021.
Net sales for the Strategic Brands segment were $154.7 million for the six-months ended June 30, 2021, an increase of approximately $30.6 million, or 24.7% higher than net sales of $124.1 million for the six-months ended June 30, 2020. Net sales for the Strategic Brands segment increased primarily due to increased worldwide sales by volume of our NOS®, Predator® and Mother® brand energy drinks as a result of increased consumer demand. Net changes in foreign currency exchange rates had a favorable impact on net sales of approximately $3.1 million for the Strategic Brands segment for the six-months ended June 30, 2021.
Net sales for the Other segment were $13.6 million for the six-months ended June 30, 2021, an increase of approximately $1.9 million, or 16.0% higher than net sales of $11.7 million for the six-months ended June 30, 2020.
Case sales, in 192-ounce case equivalents, were 300.0 million cases for the six-months ended June 30, 2021, an increase of approximately 67.5 million cases or 29.0% higher than case sales of 232.6 million cases for the six-months ended June 30, 2020. The overall average net sales per case (excluding net sales of AFF Third-Party Products of $13.6 million and $11.7 million for the six-months ended June 30, 2021 and 2020, respectively, as these sales do not have unit case equivalents) decreased to $8.97 for the six-months ended June 30, 2021, which was 2.7% lower than the average net sales per case of $9.22 for the six-months ended June 30, 2020. The decrease in the average net sales per case was primarily the result of geographical sales mix.
Gross Profit. Gross profit was $1.55 billion for the six-months ended June 30, 2021, an increase of approximately $255.1 million, or 19.7% higher than the gross profit of $1.30 billion for the six-months ended June 30, 2020. The increase in gross profit dollars was primarily the result of the $549.8 million increase in net sales for the six-months ended June 30, 2021.
Gross profit as a percentage of net sales decreased to 57.4% for the six-months ended June 30, 2021 from 60.1% for the six-months ended June 30, 2020. The decrease for the six-months ended June 30, 2021 was primarily the result of geographical sales mix and increased input costs (mainly increased raw material freight-in costs and aluminum can costs).