The Nasdaq composite index finished the week lower after major sell-offs in Microsoft and Alphabet shares after the two companies reported disappointing quarterly earnings. Pictured: Nasdaq signage is seen in New York City. Roberto Machado Noa/LightRocket via Getty Images

Weak earnings reports from Silicon Valley stalwarts sent technology stocks plunging Friday in their worst day since early February. The Dow Jones Industrial Average and Standard & Poor’s 500 index both recorded gains for the second straight week, but the sell-off tipped the comparatively tech-heavy Nasdaq composite index into negative territory for the week.

“Part of it may just be the market is taking a breather off the rally we had at the beginning of April,” Lance Humphrey, portfolio manager at USAA Asset Management in San Antonio, told CNBC. “It doesn’t feel panicky.”

Still, the Nasdaq has been in the red since the beginning of the year, with the tech sector seeing big sell-offs in both early January and early February over concerns that the sector was overbought and overvalued amid a global slowdown in growth and a strong U.S. dollar that hurts profits earned in foreign currencies.

Weak earnings in the first three months of the year by tech majors haven’t helped sentiment. Wall Street has low expectations for the current earnings season, so when companies miss already-low expectations, investors get nervous.

Microsoft’s equity closed down more than 7 percent, at $51.78, as it experienced its worst day in a year, while Google parent Alphabet’s stock finished more than 5 percent lower, at $737.77. Together, the two companies lost almost $60 billion in market value during the last trading session of the week as analysts cut price targets for their shares.

Microsoft reported after the market close Thursday a 6 percent drop in fiscal third-quarter revenue, to $20.5 billion, and a 25 percent plunge in earnings, to $3.8 billion, or 47 cents per share, compared with the same period a year ago. Weakness in its cloud computing business was a primary factor.

Alphabet also missed top- and bottom-line estimates with first-quarter earnings per share of $7.50 on $20.26 billion in sales vs. the expected $7.97 on $20.37 billion. The company cited disappointing results in operations outside its core Google search business, such as Fiber, Nest and Verily. Like other American firms doing business globally, Google also pointed to the currency headwind of a strong U.S. dollar, in addition to falling advertising rates.

The market bloodbath for the two tech giants Friday came as the rivals made peace on another front: antitrust complaints. Microsoft and Alphabet have agreed to stop going after each other by filing regulatory complaints in U.S. and foreign courts. The two have long squabbled over issues such as how Microsoft lures Windows operating system users toward its own web browser and how Alphabet’s Google purportedly manipulates search results in its favor.

“Microsoft has agreed to withdraw its regulatory complaints against Google, reflecting our changing legal priorities,” a Microsoft representative told ZDNet. Google made a similar commitment.