S&P 500 hits record close as Omicron fears ebb

Stocks rose sharply for a third straight session on Thursday, after more encouraging news in the fight against the Omicron variant, lifting investors' spirits ahead of the Christmas break and the S&P 500 to a record-high close.

The three straight days of broad gains across Wall Street's main indexes followed three straight days of losses.

Jaime Desmond, the chief operating officer at Ladenburg Asset Management said the bounceback is proof of the market's resiliency.

"Well, I think this pattern of volatility is pretty consistent with what we've experienced all year and, quite frankly, about a year and a half now. So, we've had positive news come out economically. But if the headlines were led by COVID and the Omicron variant, then they seem to dominate, quite frankly, the market performance. So, what we've proven time and time again is that the market is resilient. The consumer is resilient. And despite any negative headlines, although they may shake us for a day or two, overall, the economy is strong and growing and recovering. And we see that it just takes a few days to bounce back."

Vaccine makers AstraZeneca and Novavax said their shots protected against Omicron, as UK data suggested it may cause proportionally fewer hospital cases than the Delta variant, though public health experts warned the battle against COVID-19 was far from over.

In another medical development against the pandemic, the FDA authorized Merck's antiviral pill for COVID-19 for certain high-risk adult patients, a day after giving a broader go-ahead to a similar but more effective treatment from Pfizer.

While the news may have boosted stocks broadly, shares of both Merck and Pfizer fell - down roughly half a percent and almost a percent and half respectively.

Shares of Tesla, meanwhile, jumped for a second straight day, after CEO Elon Musk said on Wednesday he was "almost done" with his stock sales after selling over $15 billion worth since early November.

The stock market will be closed on Friday in observance of the Christmas holiday.