By Caitlin Ostroff

Here's what we're watching ahead of Tuesday's opening bell.

-- U.S. stock futures climbed ahead of a slew of earnings releases and testimony by Janet Yellen in which she is expected to support higher coronavirus relief spending.

Futures tied to the S&P 500 rose 0.6%, pointing to a rally after the opening bell. Those linked to the Nasdaq-100 added 0.9%, suggesting gains in tech stocks. Read our full market wrap here.

What's Coming Up

-- Janet Yellen, President-elect Joe Biden's choice for Treasury secretary, is set to testify before the Senate Finance Committee, which is considering her nomination, at 10 a.m. ET. She is expected to tell lawmakers that the U.S. risks a longer recession unless Congress approves more aid and affirm the commitment to market-determined exchange rates.

-- Quarterly results from Goldman Sachs are expected before the open. Netflix will report after markets close.

Market Movers to Watch

-- Shares in videogame retailer GameStop rose more than 14% premarket. The company has recently been a favorite among individual traders who have encouraged others to scoop up the stock on social media forums.

-- Coherent climbed 31% in premarket trading after Lumentum Holdings confirmed Tuesday that it would acquire the laser maker. The Wall Street Journal reported earlier that Lumentum was in advanced talks to buy Coherent. Shares in Lumentum fell 5% premarket.

-- Tesla rose 1.8% premarket after the electric car maker delivered its first made-in-China Model Y compact crossover vehicles on Monday.

-- Shares in Triterras gained more than 20% premarket after the financial technology company authorized a share repurchase program of up to $50 million.

-- Shares in Gritstone Oncology rallied more than 35% after the biotechnology company said it is advancing development of a vaccine against the virus that causes Covid-19.

-- Shares of Western Union shot up 6.4% in premarket trading, after the money-movement company announced a new agreement with Walmart in which money transfer services will be enabled at Walmart stores nationwide.

Market Fact

In the past four years, U.S. government debt held by the public has increased by $7 trillion to $21.6 trillion. At 100.1% of gross domestic product, the debt already exceeds the annual output of the economy, putting the U.S. in company with economies including Greece, Italy and Japan.

Chart of the Day

U.K. merger activity slumped in the early summer from the year-earlier period as part of a broader decline amid virus-induced lockdowns, but the fourth quarter marked a rebound in mergers and acquisitions in the U.K. as a vaccination program raised the prospect of bringing the virus under control.

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(END) Dow Jones Newswires

01-19-21 0710ET