The reached an all-time high on Monday, but the session's gains were kept in check as investors braced for a busy week including a flurry of corporate earnings reports, economic data and an announcement from the Federal Reserve.
The broad index gained 0.1% to 2,943.03, breaking the previous record high set in September. Financials led the gains in the S&P 500, climbing 0.9%. Bank of New York Mellon and Citigroup were among the best performers in the sector, rising about 2% each.
The tech-heavy Nasdaq Composite also hit an all-time high, rising 0.2% to 8,161.85. The Dow Jones Industrial Average closed 11.06 points higher at 26,554.39 as Goldman Sachs outperformed.
"This may be the busiest week of everything in terms of catalysts," said Art Hogan, chief market strategist at National Securities. "It makes sense for us to be sideways heading into that at best."
Stocks have been on a tear this year, with the S&P 500 rallying more than 17% while the Nasdaq is up 23%. The two indexes also notched record closing highs last week.
About 150 S&P 500 companies are scheduled to release their quarterly results this week, including Apple, General Electric and Qualcomm. Alphabet released its numbers after the bell on Monday.
Earlier on Monday, Restaurant Brands reported weaker-than-expected earnings after a surprise drop in Tim Hortons sales, sending its shares down 22%. Spotify Technology posted a bigger-than-forecast loss, offsetting news that it reached 100 million subscribers for its premium service. Shares of Spotify fell 0.1%.
Through Monday morning, 231 companies in the S&P 500 have reported quarterly results. Of those companies, 77.5% have topped analyst expectations, according to data from FactSet. The reported earnings growth rate, meanwhile, is around 1%, well above the expected 4.2% drop.
"Everyone has forgotten the term earnings recession," Hogan of National Securities said. "It was a bad case of premature extrapolation to think we were going to have an earnings recession."
Strong corporate reports helped push the S&P 500 and Nasdaq up by 0.9% and 1.9%, respectively, last week.
"From a technical perspective, the SPX is back in record high territory after closing above its September '18 high," Craig Johnson, chief market technician at Piper Jaffray, said in a note. "However, for a record high week, volume was lackluster and only a relatively small percentage of constituents registered new highs."
"Improving fundamentals and FOMO sentiment have pushed stocks back into record high territory," Johnson said. "Overbought conditions have now developed and market breadth has not confirmed the recent breakout. We believe some consolidation is likely and advise investors to consider realizing some gains at this juncture."
On the data front, April's nonfarm payrolls report is scheduled for release Friday along with international trade numbers. Factory orders, construction spending and consumer confidence data are all due for release this week.
The core personal consumption expenditures index — the Fed's preferred measure of inflation — remained unchanged in March, data released Monday showed. Economists polled by Refinitiv expected a gain of 1.7%.
The Fed is also set to hold a monetary policy meeting this week. Investors will be looking for clues about the central bank's plan for its balance sheet moving forward, as well as hints on where Fed officials think the economy is headed.
Market expectations for a Fed rate hike are zero, while expectations for no change in the overnight rate are at 97%, according to the CME Group's FedWatch tool.
—CNBC's Silvia Amaro contributed to this report.