I trust you've all seen copies of our press release, which was released yesterday afternoon. First, however, I would like to remind you that except for historical information, the matters that we will be describing this morning will be forward-looking statements that are dependent on certain risks and uncertainties, including such factors, among others, as new orders received and shipped during the quarter, the timely introduction of new processes and products and the general conditions in the world economy and financial markets.In addition to these risks, which we described in our press release issued yesterday, we refer you to the risk factors listed in the company's Form 10-Q for the quarter ended April 1, 2012, particularly management discussion and analysis of financial condition and results of operations. Secondly, SEC Regulation FD regarding selective disclosure influences our interaction with investors. We've opened up this conference call to enable all interested investors to listen in. The press release and this conference call will be our forum to respond to questions regarding our estimated financial performance going forward. Consequently, should you have any questions regarding our estimates of sales and profits or other financial matters to the upcoming quarter, as well as how they might impact our income statement model and our balance sheet, this is the time we're free to respond to these questions. As you can tell from our press release, we continued our growth of the previous quarter and believe our business could improve in the upcoming September quarter. Going into the quarter, although cautioning about global economic environment, we forecasted that our business would grow. We were coming off broadly distributed booking strength and we believe that inventories worldwide at customers were relatively tight exiting the March quarter. The quarter unfolded largely as we expected, although worldwide, macroeconomic concerns were greater at the end of the quarter than when we begun the quarter. In summary, we reported revenue results for the quarter at the midpoint of our guidance. Overall, bookings grew over last quarter. There were no significant changes in our end markets, with industrial and computer growing, partially offset by Automotive and Military and Space.
Cancellations were minor. We had a positive book-to-bill ratio for the quarter. Sales increased by 6%. Gross margin improved from 75.1% to 75.4%. We had similar shutdowns in our factories compared with last quarter, therefore not impacting gross margin positively or negatively. Average selling price, at $1.82 versus $1.81 last quarter, was relatively constant. The modest improvement in gross margin percentage was due to absorbing certain fixed costs over a larger sales base, and we still have a good ways to go to run at full capacity.Operating expenses increased modestly by $2.5 million or 3%, mostly due to increases in labor and profit sharing. As we forecasted, operating income increased by $11.4 million or 8%. Operating income at 45.9% of sales improved from 44.8% last quarter. Below the line, interest income and expense was largely unchanged. Finally, income taxes increased this quarter. Our quarterly effective tax rate was 26.5% as forecasted, compared with 23.75% last quarter, which had benefited from a nonrecurring discrete tax benefit. The resulting net income of $103,326,000, an improvement of $4.8 million or 5% over last quarter, is due mostly to the increase in sales, with increases in operating income being offset by an increase in the tax rate. Our return on sales of 31.3% was similar to last quarter's 31.5%. Headcount increased marginally, primarily in the R&D and sales areas as worldwide manufacturing headcount was largely unchanged. In summary, the effect of the items I just listed on the published quarterly results was that revenue was $330 million for the fourth quarter of fiscal year 2012 compared to the previous quarter's revenue of $312.4 million and $358.6 million reported in the fourth quarter of fiscal year 2011. GAAP diluted earnings per share of $0.44 increased $0.02 from the previous quarter's earnings per share and decreased $0.24 from the $0.68 EPS reported in the fourth quarter of fiscal 2011, which had benefited from higher sales and an uncommonly low quarterly effective tax rate of 9.5%.
GAAP net income was $103.3 million compared with $98.5 million last quarter and $158.2 million reported in the fourth quarter of last year. Earnings per share would be $0.50 on a pro forma basis, which excludes the impact of stock option accounting and the amortization of debt discount, which is the theoretical difference between the company's convertible debt, actual interest and the interest it would potentially have had to pay if it had used straight bank debt.During the June quarter, the company's cash and short-term investments balance increased by $91.2 million to $1,203,000,000. The company announced that it would again pay a quarterly dividend of $0.25 per share. This cash dividend will be paid on August 29 to stockholders of record on August 17. Read the rest of this transcript for free on seekingalpha.com