The Fed begins its two-day meeting Tuesday, but earnings from Apple after the closing bell may create a bigger trading event.

There are dozens of major earnings during Tuesday morning hours, with BP, Procter & Gamble, 3M and Eli Lilly among them. But Apple stands tall after the closing bell, following a series of high-profile tech misses and expectations for Apple's profits and revenues to decline. Twitter and AT&T also report after the close.

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Apple is expected to report earnings fell to $1.99 from $2.33 per share, on revenues of $52 billion, down from $58 billion, according to Thomson Reuters. That would be the first quarter in 51 in which Apple's revenues would have actually shrunk.

Apple has lost some of its shine as a tech darling, but it still has big impact and is part of the Dow, S&P 500 and Nasdaq. In the past eight quarters, Apple rose 63 percent of the time on the day after earnings, for a gain of 1.25 percent, according to analytics firm Kensho. Its worst performance in those eight quarters was last quarter when Apple missed and iPhone sales disappointed. Its stock fell more than 6.5 percent.

Stocks were squishy Monday, as the S&P 500 lost three points to 2,087 as oil weakened. West Texas Intermediate crude futures were down 2.5 percent at $42.64 per barrel, as over-supply worries again bubbled up.

"I think there'll be a lot of eyes on Apple, and on earnings in general," said Steve Massocca of Wedbush Securities. S&P 500 companies' earnings are expected to decline by 7.3 percent in the first quarter, though more than 70 percent of companies reporting so far have beaten estimates, according to Thomson Reuters. Massocca says he does not believe that earnings have bottomed, a view shared by many analysts.

"I think [the stock market] is due for a little pullback, quite frankly. I think it's a little overbought," he said of the stock market. "The S&P at 17 times [earnings] is not cheap. I think the current monetary regime is a stock market flotation device."

Other earnings expected Tuesday include DuPont, Coach, Corning, Lockheed Martin, Whirlpool, Hershey, Freeport-McMoran, AK Steel, T. Rowe Price, Whirlpool and Tenneco. After the bell reports are expected from eBay, Chipotle, Capital One, Buffalo Wild Wings, Panera Bread, U.S. Steel, KLA-Tencor, Akamai, Aflac and TransUnion.

Read More From CNBC: Apple Could Shrink for the First Time Since 2003