Tech stocks just had their worst two-week stretch since the start of the pandemic

What started off as a third-quarter rebound has turned into a flop for tech investors.

The Nasdaq Composite tumbled 5.1% this week after losing 5.5% the prior week. That marks the worst two-week stretch for the tech-heavy index since it plunged more than 20% in March 2020 at the start of the Covid-19 pandemic in the U.S.

With the third quarter set to wrap up next week, the Nasdaq is poised to notch losses for a third straight quarter unless it…