March 18 (Reuters) - Wall Street's main indexes advanced on Monday, with megacap growth stocks such as Alphabet and Tesla supporting a rebound in technology-heavy Nasdaq while investors also waited for the U.S. Federal Reserve's meeting this week.

Google's parent Alphabet provided a sizeable boost to the market after a media report that Apple is in talks to build Google's Gemini AI engine into the iPhone.

This boosted the communication services sector, which lead gains among the 11 major S&P 500 sectors and hit its highest level since Sept. 2021.

Tesla shares also helped boost indexes as shares in the electric carmaker gained after it said it would soon increase the price of its Model Y EVs in parts of Europe.

Nvidia shares advanced but pared earlier gains. The artificial intelligence poster-child kicked off its annual developer conference, with investors waiting for new chip announcements from Chief Executive Jensen Huang after the close.

Investors were torn between enthusiasm about the prospects for AI on the technology sector and worries ahead to the Federal Reserve's statement and commentary on Wednesday according to Lindsey Bell, chief strategist at 248 Ventures in Charlotte, North Carolina.

"This is a market that really wants to hold onto the momentum trade but what's really weighing on investors' minds is what happens with the Fed this week," said Bell.

"The market is sitting comfortably with the first cut coming in June or July but not entirely confident it'll be the case. The question is if it gets pushed out further."

According to preliminary data, the S&P 500 gained 32.48 points, or 0.63%, to end at 5,149.57 points, while the Nasdaq Composite gained 130.28 points, or 0.82%, to 16,103.46. The Dow Jones Industrial Average rose 73.44 points, or 0.19%, to 38,788.21.

Stronger-than-expected inflation figures have prompted traders to rethink when and by how much policymakers will lower rates this year, with traders pulling back the probability for a June rate cut to around 51% from about 71% just a week ago, according to the CME FedWatch Tool.

If the Fed were to take a hawkish tone when its policy meeting concludes on Wednesday, this could pressure stocks.

"The fact we're up today provides investors with an opportunity to take profits ahead of the Fed which is more likely to disappoint than to support the recent rally in risk assets," said Sameer Samana, Senior Global Market Strategist at Wells Fargo Investment Institute in Charlotte.

Goldman Sachs on Monday said they now expect three interest rate cuts in 2024, compared with four expected earlier, after inflation came in a bit firmer than expected.

"With the market near recent highs its very difficult to see what could provide an upside spark from here. It's not hard to imagine the things that could cause disappointment," said Samana citing the Fed and high valuations for tech stocks.

Exchange operator Nasdaq said it resolved an issue related to connectivity and stock orders that had affected early trading for more than two hours on Monday.

U.S.-listed shares of Xpeng climbed on its plans to launch a cheaper EV brand amid fierce price competition.

Boeing fell after a media report that a federal grand jury in Seattle issued a subpoena to the planemaker over the Jan. 5 midair blowout of a Boeing door plug on an Alaska Airlines flight.

Super Micro Computer, which joined the S&P 500 on Monday, gave up earlier gains. However, the stock, which has been boosted by bets it would benefit from AI, is still up sharply for the year-to-date. (Reporting by Sinéad Carew in New York, Bansari Mayur Kamdar and Shashwat Chauhan in Bengaluru; Editing by Pooja Desai, Maju Samuel and Aurora Ellis)