an increase in acquisition related expenses of $3.1 million related to the acquisitions of Arcturus UAV and Progeny Systems Corporation’s Intelligent Systems Group (“ISG”) and the pending acquisition of Telerob GmbH.
Other income, net, for the third quarter of fiscal 2021 was $0.1 million, as compared to $1.2 million for the third quarter of fiscal 2020. The decrease in other income, net was primarily due to a decrease in interest income resulting from a decrease in the average interest rate earned on our investment portfolio.
Benefit from income taxes for the third quarter of fiscal 2021 was $0.9 million, as compared to $38 thousand for the third quarter of fiscal 2020. The increase in benefit from income taxes was primarily due to a decrease in the projected fiscal year 2021 effective tax rate.
Equity method investment loss, net of tax, for the third quarter of fiscal 2021 was $0.1 million, as compared to $1.2 million for the third quarter of fiscal 2020.
Net income attributable to AeroVironment for the third quarter of fiscal 2021 was $0.2 million, as compared to a net loss attributable to AeroVironment of $1.0 million for the third quarter of fiscal 2020.
Earnings per diluted share attributable to AeroVironment for the third quarter of fiscal 2021 was $0.01, as compared to a loss per diluted share attributable to AeroVironment of $0.04 for the third quarter of fiscal 2020.
Non-GAAP earnings per diluted share was $0.14 for the third quarter of fiscal 2021, as compared to a loss of $0.01 for the third quarter of fiscal 2020.
FISCAL 2021 YEAR-TO-DATE RESULTS
Revenue for the first nine months of fiscal 2021 was $258.9 million, an increase of 12% from the first nine months of fiscal 2020 revenue of $232.1 million. The increase in revenue was due to an increase in product sales of $22.6 million and an increase in service revenue of $4.2 million.
Gross margin for the first nine months of fiscal 2021 was $104.9 million, an increase of 5% from the first nine months of fiscal 2020 gross margin of $99.9 million. The increase in gross margin was primarily due to an increase in product margin of $2.8 million and an increase in service margin of $2.2 million. As a percentage of revenue, gross margin decreased to 41% from 43%. The decrease in gross margin percentage was primarily due to an unfavorable product mix.
Income from operations for the first nine months of fiscal 2021 was $25.6 million, a decrease of $0.2 million from the first nine months of fiscal 2020 of $25.8 million. The decrease in income from operations was primarily a result of an increase in R&D expense of $5.8 million, partially offset by an increase in gross margin of $5.0 million and a decrease in SG&A expense of $0.5 million. SG&A expense for the first nine months of fiscal 2021 includes an increase in acquisition related expenses of $3.1 million related to the acquisitions of Arcturus UAV and ISG and the pending acquisition of Telerob.
Other income, net, for the first nine months of fiscal 2021 was $0.5 million, as compared to $4.3 million for the first nine months of fiscal 2020. The decrease in other income, net was primarily due to a decrease in interest income resulting from a decrease in the average interest rate earned on our investment portfolio.
Provision for income taxes for the first nine months of fiscal 2021 was $2.8 million, as compared to $3.2 million for the first nine months of fiscal 2020. The decrease in provision for income taxes was primarily due to a decrease in income before income taxes.
Equity method investment loss, net of tax, for the first nine months of fiscal 2021 was $10.9 million, as compared to $3.4 million for the first nine months of fiscal 2020. Equity method investment loss, net of tax, for the first nine months of fiscal 2021 included a loss of $8.4 million for our proportionate share of the HAPSMobile Inc. joint venture’s impairment of its investment in Loon LLC.