What happened

Shares of Fluidigm (FLDM 1.02%) plummeted on Thursday after a powerful rival announced a major development in the COVID-19 diagnostic race.

So what 

What a difference a day makes. After soaring 30% on Wednesday following news that its saliva-based coronavirus test had received an emergency use authorization from the U.S. Food and Drug Administration (FDA), Fluidigm gave up all of those gains today.

A stock chart that rises then falls, with a section that continued to rise wiped away.

Fluidigm's stock made a round trip over the past two days. Image source: Getty Images.

Yesterday, investors were excited about the potentially massive market opportunity for Fluidigm's new test. Today, however, they're decidedly less so, following news that healthcare giant Abbott Laboratories (ABT 0.04%) had also been granted an emergency use authorization by the FDA. 

Now what 

Abbott's test reportedly costs only $5 and can deliver results in just 15 minutes. It also requires no special lab equipment. And its results can be displayed via a free app that Abbott says could potentially be used as a "temporary digital health pass." The healthcare titan expects demand to be strong for its new test, and it's ramping up production to be able to provide 50 million tests per month beginning in October. 

For these reasons -- and although it's not a saliva-based test, like that of Fluidigm -- Abbott's test is considered to be a major breakthrough in the battle against COVID-19. In turn, investors reset their growth expectations for Fluidigm, and its stock price fell in kind.