The tech-heavy Nasdaq Composite Index saw its best annual return since 2009, rising 43.6% in 2020, aided by a 0.7% rise in the final week of 2020, a 5.7% in December, and a 15.7% in the final three months of last year.

What’s driving the market?

Markets were struggling to add to their gains amid concerns around COVID-19 in the first trading day of the year.

The global tally for confirmed cases of the coronavirus that causes COVID-19 rose above 85 million on Monday, according to data aggregated by Johns Hopkins University, while the death toll rose above 1.8 million. Some experts warned that the COVID data could be undercounted because staffing at many centers is reduced.

The rapid spread of a variant of the deadly pathogen that was first reported in Britain also has caused some cause for concerns among public health experts but the market has thus far not reacted to the mutation of COVID-19. New aggressive variants in South Africa were also raising anxieties.

U.S. vaccine czar Moncef Slaoui on Sunday said that U.S. could increase its vaccine rollout by giving out half doses of the medication developed by Moderna MRNA.

Meanwhile, Wall Street is also keeping an eye on Georgia as runoff elections for two U.S. Senate seats have the potential to inject volatility into markets that have thus far looked past political turbulence in Washington and focused on recent fiscal spending measures and easy-money policies out of the Federal Reserve.

Market participants say any complacency among investors could be misplaced, since if the Democrats win both Senate seats, which could help President-elect Joe Biden reverse the corporate tax cuts of 2017, putting company earnings and stock prices under some pressure.

Read: Why the Georgia runoff elections for the U.S. Senate could turn into a ‘big deal’ for markets

Investors saw some manufacturing sector data in Asia and Europe that was better than expected, reflecting improvement from the stultifying levels of economic expansion prevalent during the pandemic, according to surveys of purchasing managers for December.

In U.S. economic data, the final IHS Markit manufacturing survey for December was upgraded to a reading of 57.1, compared with an initial reading of 56.5. A report on construction spending is due at 10 a.m.

Investors also will watch for speeches from a number of Fed officials, including Chicago Fed President Charles Evans, Atlanta Fed President Raphael Bostic, and Cleveland Fed President Loretta Mester, who will speak at an annual meeting on the post-pandemic economy hosted by the American Economics Association.

Which stocks were in focus?

Teledyne Technologies Inc. TDY  plans to acquire Flir Systems Inc.  FLIR  in a cash-and-stock deal valued at about $8 billion. Teledyne was down 4%.

Health care insurer Centene Corp.  CNC  said Monday it has agreed to acquire Magellan Health Inc. MGLN  for $95 a share, in a deal with an enterprise value of $2.2 billion. Centene Corp. shares were up 0.4%.

Dentsply Sirona Inc. XRAY  shares gained over 4% after it announced its acquisition of Byte, a privately owned clear dental-aligner provider, in an all-cash deal valued at $1.04 billion.

Shares of U.K. gaming company Entain jumped 31% after rejecting the proposed 1,383 pence per share bid from MGM Resorts MGM that valued the company at £8.09 billion.

Which assets are on the move?

The 10-year Treasury note yield BX:TMUBMUSD10Y was up 2.1 basis points to 0.933%. Bond prices move in the opposite direction of yields.

February U.S. benchmark crude futures CL were down 0.3% to $48.39 a barrel, while gold GCG21 rose 2.3% to $1,937.90 an ounce.

The dollar against its major rivals fell 0.5%, based on the ICE U.S. Dollar Index. DXY

The pan-European STOXX Europe 600 index FXXP00 was gaining 1.5%, and the U.K.’s FTSE 100 UK:UKX rose 2.8%. The Shanghai Composite CN:SHCOMP and Hong Kong’s Hang Seng index HK:HSI both close 0.9% higher, while Korea’s Kospi KR:180721 surged 2.5%.