Google’s traffic acquisition costs, the amount it pays to its partners and a closely watched measure of its expenses, was essentially flat at $1.15 billion in the quarter compared with $1.14 billion in the first quarter. The vast majority of this was paid to AdSense advertising partners, while a much smaller portion was paid to partners who send users to Google’s web sites.

    International growth remainedstrong for Google as it continued to invest overseas. International revenues were $1.84 billion, or 48 percent of total revenues, in the second quarter, compared with 42 percent in the same period last year.

    Investors were spooked by the results, dropping the stock from a market close of $548.59 to an after-hours trading price of $508.63, a 7.28 percent drop, shortly after the company’s conference call.