Every three months, corporate America gives investors a look at its books — offering updates on how sales and profits fared in the latest quarter, and usually providing a sense of what to expect from the rest of the year.

It can be an important period for the stock market, as traders learn how well their expectations matched up with reality. With the pandemic raging and the recovery floundering, earnings seasons gives investors another bead on the state of the economy.

(Earlier this month, for example, several big banks said they were cutting down reserves meant to protect against a downturn — a clear sign that they’re feeling better about things — and the news helped bolster stocks.)

But the latest earnings season also comes at a time when investors are starting to wonder if the stock market’s rally has gone too far, and whether stocks are in a bubble as prices become increasingly detached from a company’s profits and growth prospects.

How Wall Street reacts to the incoming results could help show how important (or unimportant) earnings, sales and growth are to share prices.

This week is the busiest of the fourth-quarter earnings season, with results expected from a third of the companies in the S&P 500 — including technology giants Microsoft, Apple, Facebook and Tesla. Overall, Wall Street analysts expect that profits at S&P 500 companies will be down 7 percent compared with the fourth quarter of 2019, according to FactSet data.

So far, results from the first 66 companies in the S&P 500 that reported earnings have been slightly stronger than usual. About 88 percent of those companies did better than analysts expected. Wall Street is notorious for underestimating how companies will do, but that share of companies that “beat” is higher than what’s typical.

Strangely, however, investors have seemed downright dismissive of better-than-expected earnings results, and that could be a bad omen for the market.

Usually, when a company does better than expected, its shares rise. But, through Friday, companies that beat expectations have actually underperformed the broader market, according to Bank of America analysts.

Such a reaction is yet another indication that stock prices are becoming increasingly untethered from fundamentals. In fact, Bank of America analysts noted that they haven’t seen this sort of reaction to earnings results since the dot-com bubble was beginning to deflate.

“The last time we saw such a perverse market reaction to earnings was during 2Q 2000 earnings season, after which the S&P 500 fell by 13 percent over the next three months,” they wrote.

The International Monetary Fund upgraded its outlook for the world economy on Tuesday as the rollout of coronavirus vaccines raised expectations for a stronger recovery in 2021.

The rosier outlook is welcome news for a global economy that has been battered by the coronavirus pandemic in the past year, forcing lockdowns and strict social distancing measures that have sapped business activity.

An updated World Economic Outlook report projected that the global economy will grow 5.5 percent this year after contracting by 3.5 percent in 2020. The forecast was 0.3 percentage point stronger than the fund’s October estimate.

The I.M.F. said that the economic rebound remains uneven, with some economies better able to prop up their economies with fiscal stimulus measures. It predicted the United States economy will expand by 5.1 percent this year, the euro-area economy will expand by 4.2 percent and Japan’s economy will expand by 3.1 percent.

Emerging market economies are projected to expand by 6.3 percent. In China, where the outbreak first surfaced, the economy is expected to expand by 8.1 percent.

Despite the upbeat forecast, the I.M.F. warned that the world economy is not yet in the clear. The logistics of the vaccine rollout could face obstacles and new variants of the virus present a threat. And it remains unclear how immunity to the virus will affect economic activity after so many months of strain.

“Much remains to be done on the health and economic policy fronts to limit persistent damage from the severe contraction of 2020 and ensure a sustained recovery,” the report said.

Twitter said it had permanently barred Mike Lindell, the chief executive officer of the bedding company MyPillow and a close ally of former President Donald J. Trump, from its service.

The move on Monday night followed numerous tweets by Mr. Lindell promoting debunked conspiracy theories about election fraud.

Mr. Lindell’s Twitter account, which had nearly 413,000 followers, was permanently suspended “due to repeated violations of our Civic Integrity Policy,” said Lauren Alexander, a Twitter spokeswoman, in an email.

Corporate America has moved swiftly to try to turn down the volume on assertions by Mr. Lindell, a major Republican donor and one of the loudest voices perpetuating Mr. Trump’s claims of voter fraud in the Nov. 3 elections. Kohl’s and Bed Bath & Beyond removed MyPillow products from their stores last week.

Mr. Lindell also faces legal action over his claims of voting fraud involving Dominion Voting Systems, the company at the center of one of the more outlandish conspiracy theories about voter fraud.

His account’s suspension is the latest in a series of high-profile bans by Twitter since the company permanently blocked Mr. Trump from its service over concerns that he would use the platform to incite more violence like the storming of the Capitol this month.

After the attack on the Capitol, Twitter said it had updated its rules to more aggressively police false or misleading information about the presidential election. As part of that move, Twitter has moved to suspend the accounts of more than 70,000 people who have promoted content related to QAnon, a fringe pro-Trump group that the F.B.I. has labeled a domestic terrorist threat.

The Senate confirmed Janet L. Yellen to be Treasury secretary on Monday, putting her at the forefront of navigating the fallout created by the pandemic as she advocates for President Biden’s economic agenda.

Ms. Yellen, the former Federal Reserve chair, was confirmed by a vote of 84 to 15 with support from both Republicans and Democrats. She is the first woman to hold the top job at Treasury in its 232-year history.

With the confirmation, she will now be thrust into the middle of negotiations over a potential $1.9 trillion economic aid package that is the chief plank of Mr. Biden’s effort to revive the economy. The size of the plan already met with doubts from some Democrats and Republicans.

Ms. Yellen has been a clear champion of continued government support for workers and businesses, publicly warning that a lack of aid to state and local governments could slow the recovery, much as it did in the aftermath of the Great Recession.

At her confirmation hearing and in written responses to lawmakers, Ms. Yellen echoed Mr. Biden’s view that Congress must “act big” to prevent the economy from faltering and defended using borrowed money to finance another aid package, saying not doing so would leave workers and families worse off.

“The relief bill late last year was just a down payment to get us through the next few months,” Ms. Yellen said. “We have a long way to go before our economy fully recovers.”

U.S. markets

• U.S. stock futures indicated indexes on Wall Street would open little changed from Monday. The S&P 500 has drifted near a record high for the past week.

• Janet Yellen was confirmed as Treasury secretary on Monday and investors will be watching how she and the Biden administration move forward a $1.9 trillion stimulus proposal. Over the weekend, lawmakers from both political parties questioned whether such a large package was needed, while others expressed the need to make more aid available quickly.

• Shares in GameStop, a struggling video game retailer, continued to rally in premarket trading on Tuesday. The shares have already jumped 300 percent this year as small investors have piled into options on the company, placing risky bets that the price of the stock will keep going higher.

Europe

• Most European indexes gained, led by corporate deals. Shares in Naturgy Energy, a Spanish utilities company pivoting to renewable energy, rose more than 16 percent after IFM, an investment company, offered to buy a large stake. Shares in EQT, a large Swedish private equity firm, jumped 14 percent after it bought a U.S.-based real estate company, Exeter Property Group.

• The Stoxx Europe 600 index rose 1 percent.

• European stocks and government bonds have proved resilient to the political turmoil in Italy. Prime Minister Giuseppe Conte is expected to resign on Tuesday. He’s struggled to regain support after a junior partner in his coalition government pulled out earlier this month.

British unemployment

• Britain’s unemployment rate rose to 5 percent in the September-November period, the highest level in four and a half years. Although the government’s furlough program has prevented the rate from surging higher, there are some signs that the labor market was losing momentum late last year, during the second wave of the pandemic. For example, the number of job vacancies increased by 81,000, almost half the number from the previous quarter.

• “While the labor market continued to deteriorate, the furlough has held back the tide on jobs losses,” said Nye Cominetti, an economist at the Resolution Foundation, a think tank. “Around one-in-six private sector workers were furloughed during England’s second lockdown in November, and even more are likely to be furloughed today.”

Asia

• Asian stock indexes dropped on Tuesday after China’s central bank withdrew cash from the banking system and an adviser to the central bank warned about bubbles in asset prices including stocks and property.

• The Hang Seng index in Hong Kong closed 2.5 percent lower. On Monday, it had climbed to a one-year high.

Bankruptcies fell 40 percent last year in France and Britain, and were down 25 percent on average in the European Union.

By contrast, Chapter 11 bankruptcy filings in the United States rose in the third quarter to the highest level since the 2010 financial crisis, a trend that is expected to continue in 2021, according to an index compiled by the U.S. law firm Polsinelli.

The difference is the enormous sums European countries are spending to keep businesses afloat. But some worry they’ve gone too far; bankruptcies are plunging to levels not seen in decades.

Those statistics are shaping a debate over whether Europe’s strategy of protecting businesses and workers “at all costs” will cement a recovery, or leave economies less competitive and more dependent on government aid when the pandemic recedes.

Letting unviable businesses go under, while painful, will be essential for allowing competitive sectors to thrive, said Jeffrey Franks, the head of the International Monetary Fund’s mission for France.

A wave of bankruptcies “is not something that’s necessarily so bad,” he said. “It’s part of the normal creative destruction process of regenerating economies.”

• Leon Black, the chief executive and chairman of Apollo Global Management, announced his plan on Monday to step down as chief executive this year. The move follows an inquiry by the firm that revealed that Mr. Black had paid $158 million to the convicted sex offender Jeffrey Epstein in a five-year period ending in 2017. He had also lent Mr. Epstein more than $30 million, only $10 million of which was paid back, the report found. Mr. Black’s payments effectively bankrolled the lifestyle of Mr. Epstein in the years after his 2008 guilty plea in Florida to a prostitution charge involving a teenage girl.

• The Norwegian Data Protection Authority said on Monday that it would fine Grindr, the world’s most popular gay dating app, 100 million Norwegian Kroner, or about $11.7 million dollars, for illegally disclosing private details about its users to advertising companies. The Norwegian agency said the app had transmitted users’ precise locations, user-tracking codes and the app’s name to at least five advertising companies, essentially tagging individuals as L.G.B.T.Q. without obtaining their explicit consent, in violation of European data protection law.