What happened

Shares of Fastly (FSLY -2.14%) were climbing today on no company-specific news. The tech stock was likely rising today as the optimism in the broader market was driving the S&P 500 higher. 

Fastly's stock was up by 5.5% as of 2:36 p.m. EDT.

So what

The S&P 500 was up by 1% at the time of this writing, and the Nasdaq Composite, which consists of many tech stocks, had gained 1.6%. 

A white line graph on a dark background.

Image source: Getty Images.

Investors may be optimistic about the market in general today after the U.S. Food and Drug Administration granted full approval of the COVID-19 vaccine co-created by Pfizer and BioNTech. The vaccine had formerly received emergency approval by the FDA. 

Additionally, investors may be flocking back to some tech stocks, including Fastly, as the delta variant of the coronavirus continues to spread across the U.S. 

Some investors have shifted their attention back to so-called pandemic stocks because rising COVID-19 cases have forced many companies to pause their plans for bringing employees back into the office. 

Fastly's services help companies deliver internet content to users, and if some reopening plans are put on hold, it could mean that people are more likely to be streaming video services and spending time online.

Now what 

Fastly's management says that full-year 2021 revenue will be in the range between $340 million and $350 million, which would be up from $291 million in 2020. But some investors have questioned the company's growth potential after it experienced a major outage earlier this summer. The exodus from Fastly's stock has left its share price down 50% year to date.