Stocks close mixed ahead of Fed statement; Twitter plunges 18%

U.S.stocks closed mixed on Tuesday as investors eyed tech earnings and awaited the Federal Reserve's statement on Wednesday. ( Tweet This )

Twitter had its second-worst day, with shares closing down 18.18 percent. In the last 15 minutes before the close, shares resumed trading about 20 percent lower. The company was scheduled to report after the bell but released its earnings early, after shares were halted following a 5.5 percent plunge on online reports that earnings may have leaked.

The social media company reported a beat on earnings but a miss on revenue, as well as lower 2015 full-year expectations. Guidance on second-quarter revenue was about $100 million lower than estimates.

Read MoreTwitter buys a company backed by... Twitter's CEO

Tuesday's afternoon gains in equities were muted, with the Nasdaq failing to stay in positive territory, as investors remained on edge ahead of Wednesday's expected Fed statement.

"The Fed meeting has caused markets to be nervous even though there's no press conference," said Qunicy Krosby, market strategist at Prudential Financial. "There is a worry that there is a signal that they will raise rates this year."

The Federal Market Open Committee began on Tuesday and will conclude with the release of a post-meeting statement expected at 2 p.m. on Wednesday. A wave of mostly disappointing domestic data since the previous FOMC meeting has spurred economists to downgrade their outlooks for the U.S. economy in 2015, particularly for the first quarter. Signs of economic improvement in the subsequent quarters could still support a rate hike at some point later this year.

Read MoreUS markets waver ahead of Fed meeting

"The market is very content with the earnings and its a stubbornly strong market, and I suspect another reason for today's climb is investors feel confident the FOMC statement ... is not going to be (too) hawkish and interest rates stay on hold," said Peter Cardillo, chief market economist at Rockwell Global Capital.

The Dow Jones industrial average held about 70 points higher after briefly falling more than 100 points on news of the seizure of a Western cargo ship off the coast of Iran.

Oil futures pared gains after earlier rising on the same headlines. Crude oil settled up 7 cents at $57.06 a barrel on the New York Mercantile Exchange. Gold futures ended up $10.70 at $1,213.90 an ounce.

"It was a big move for a moment there. It seems with denials (that the ship was a U.S. ship)" stocks are coming back," said Dan Greenhaus, chief global strategist at BTIG. "It's all earnings."

Senior US defense officials told NBC News that Iranian Revolutionary guard forces seized a cargo ship, flagged to the Marshall Islands. According to the officials, the revolutionary forces boarded the vessel in international waters off the coast of Iran and may be taking it to an Iranian port.

The Maersk Tigris, which had no U.S. citizens abroad, was traveling through the Strait of Hormuz near the Persian Gulf when the incident occurred, a Pentagon spokesman told Reuters.

"I would say many years ago Iran news would have ... shaken (the market)," said Jack Ablin, chief investment officer at BMO Private Bank. "It doesn't appear to have as much impact as I would have thought."

Read MoreIran vessel takeover: Who probably did it—and why

Art Hogan, chief market strategist at Wunderlich Securities, noted the earlier decline in equities came amid a slightly disappointing consumer confidence figure, an Apple downgrade, and Iranian news. "It's a confluence of all three things hitting at the same time."

Apple closed down 1.6 percent as the worst performing blue chip. Earlier, the stock briefly gained to touch a new all-time high above $133.60 a share as the tech giant carried over momentum from Monday's earnings report. The company reported quarterly earnings per share of $2.33 on revenue of $56.08 billion, both above consensus estimates. Apple also said it would expand its capital return program to $200 billion from $130 billion.

Apple closed up 1.8 percent on Monday ahead of its earnings report. However, a major decline across biotechs weighed on the major indices, which failed to hold Friday's records and closed lower on Monday.

Read MoreIcahn: Apple 'undervalued and misunderstood'

Merck surged more than 5 percent, for its best day since January 2014, to lead gains in the Dow. The firm beat Wall Street's estimates after posting adjusted quarterly profits of 85 cent per share on revenue of $9.4 billion, sending the stock up more than 4.5 percent in premarket trading. Analysts expected the company to report earnings per share of 75 cents on revenue of $9.1 billion.

The euro strengthened to above $1.09, with hopes of progress on the Greece debt talks, Boockvar said. However, the stronger currency put pressure on European stocks, which closed lower.

Greek Prime Minister Alexis Tsipras said on Monday that he may resort to a referendum if lenders insist on demands that the government deems unacceptable, Reuters reported. But he added that he was confident of striking a deal to avoid such a scenario.

Read MoreVaroufakis sidelined but Greece still in danger

The Conference Board consumer confidence survey results for April was 95.2, below expectations of a rise.

The S&P/Case-Shiller's 20-City Composite gained 5 percent year-over-year in February, compared with a 4.5 percent increase in January.

"This is certainly good news at a time (when) we need good news," Hogan said. He noted while traders will focus on Apple, they have a slew of other earnings to watch.

The U.S. 10-year Treasury yield gained to 1.99 percent.

"I think that's due to the strong housing data," Cardillo said.

Reports from Samsung Electronics, Kraft Foods, GoPro, Buffalo Wild Wings are all due after the bell.

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BP closed up 1 percent after the firm managed to beat its own profit expectations in a first-quarter release.

Read MoreEarly movers: BP, F, AAPL, BMY, COH, PFE & more

Pfizer closed mildly lower, down 0.32 percent, after the company lowered its 2015 guidance for earnings per share and revenue. The pharmaceutical giant also reported quarterly adjusted profits of 51 cent per share on revenue of $10.86 billion, both of which beat Wall Street estimates.

The Dow Jones Industrial Average closed up 72.17, or 0.40 percent, at 18,110.14, with Merck leading advancers and Apple the greatest laggard.

The S&P 500 closed up 5.84 points, or 0.28 percent, at 2,114.76, with telecommunications leading nine sectors higher and consumer discretionary the only laggard.

The Nasdaq closed down 4.82 points, or 0.10 percent, at 5,055.42.

Advancers outpaced decliners about two to one on the New York Stock Exchange, with an exchange volume of 786 million and a composite volume of 3.5 billion in the close.

The CBOE Volatility Index (VIX), widely considered the best gauge of fear in the market, traded near 13.

CNBC's Tom DiChristopher, Jenny Cosgrave and Fred Imbert contributed to this report

On tap this week:

Tuesday

Fed meeting starts

Earnings: Samsung Electronics, Aflac, Akamai, GoPro, Kraft Foods, Range Resources, Twitter, Western Digital, Buffalo Wild Wings, Panera Bread, U.S. Steel

Wednesday

Earnings: Deutsche Bank, Fiat Chrysler, Northrop Grumman, General Dynamics, Hess, Starwood, Brunswick, Carlyle Group, Spirit Airlines, Norfolk Southern, Southern Co, Time Warner, Garmin, GrubHub, International Paper, Thomson Reuters, MasterCard, Marriott, Whiting Petroleum, Williams Cos, Boston Beer, Cabot, Murphy Oil, Baidu, Vertex, Yelp, Shutterfly, LaQuinta, Goodyear

8:30 a.m.: Q1 GDP, pending home sales

1:00 p.m.: $29 billion 7-year notes

2:00 p.m.: FOMC statement

Thursday

Earnings: ExxonMobil, ConocoPhllips, Royal Dutch Shell, Sanofi, Statoil, BNP Paribas, Visa, AIG, LinkedIn, Colgate-Palmolive, Celgene, Delphi Automotive, Air Products, Cigna, Cardinal Health, Sony, Time Warner Cable, Teva Pharma, Viacom, Beazer Homes, First Solar, FireEye, Dreamworks Animation, Healthsouth

8:30 a.m.: Initial claims, personal income/spending, employment cost index, Fed Gov. Daniel Tarullo

9:45 a.m.: Chicago PMI

Friday

Vehicle sales

Earnings: Chevron, CVS Health, Aon, Calpine, Clorox, Moody's, Newell Rubbermaid, Duke Energy, Weyerhaeuser, TransCanada, VF Corp, Madison Square Garden, Legg Mason, CBOE

8:30 a.m.: Cleveland Fed President Loretta Mester

9:45 a.m.: Manufacturing PMI

10 a.m.: ISM manufacturing, construction spending, consumer sentiment

3:45 p.m.: San Francisco Fed President John Williams

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