GAAP gross profit for third quarter 2017 was $96.3 million, or 33.8 percent of revenue, including approximately $2.7 million of KFAB closure costs. Non-GAAP gross profit was $99.0 million, or 34.7 percent of revenue, excluding these costs. This compares to GAAP gross profit of $90.1 million, or 34.1 percent of revenue, in the second quarter 2017 and $80.6 million, or 32.2 percent of revenue, in the third quarter 2016. The increase in gross profit margin was due primarily to continued improvements in product mix and utilization, combined with another strong quarter in North America and Europe as well as the Pericom business.

GAAP operating expenses for third quarter 2017 were $72.6 million, or 25.5 percent of revenue, and $63.9 million, or 22.4 percent of revenue, on a non-GAAP basis, which excludes $4.7 million of amortization of acquisition-related intangible asset expenses, $2.0 million of KFAB restructuring charges and $2.0 million for the impairment of fixed assets. GAAP operating expenses in the second quarter 2017 were $66.3 million, or 25.1 percent of revenue, and $59.8 million, or 22.6 percent of revenue, on a non-GAAP basis.

Third quarter 2017 GAAP net income was $14.5 million, or $0.29 per diluted share, compared to $13.2 million, or $0.26 per diluted share, in second quarter 2017 and $10.6 million, or $0.21 per share, in third quarter 2016.

Third quarter 2017 non-GAAP adjusted net income was $22.6 million, or $0.45 per diluted share, which excluded, net of tax, $3.8 million of non-cash acquisition-related intangible asset amortization costs, $3.1 million of KFAB restructuring and closure costs and $1.3 million of fixed asset impairment charges. This compares to non-GAAP adjusted net income of $17.8 million, or $0.36 per diluted share, in second quarter 2017 and $15.1 million, or $0.30 per diluted share, in third quarter 2016.

The following is an unaudited summary reconciliation of GAAP net income to non-GAAP adjusted net income and per share data, net of tax (in thousands, except per share data):