* Alphabet jumps on record profit, plans $50 billion buyback * Communication services leads gains among S&P 500 sectors * Boeing falls on wider-than-expected quarterly loss * Microsoft shares down on valuation * Indexes: Dow down 0.44%, S&P up 0.19%, Nasdaq up 0.13% (Updates to open) April 28 (Reuters) - A surge in shares of Alphabet following strong earnings drove the S&P 500 to a record high and bolstered the Nasdaq index, while investors hoped that the Federal Reserve would stick to its promise of keeping monetary policy loose. Google parent Alphabet Inc jumped 5.4% on reporting a record profit for the second consecutive quarter and announcing a $50 billion share buyback. The S&P 500 communication services sector, which houses Alphabet, added 2.3% and led gains among the 11 major S&P 500 sectors. Market participants are also prepping for results of Apple Inc and Facebook Inc after markets close. Facebook Inc is expected to report a rise in first-quarter revenue, while Apple Inc is expected to post a more than 32% jump in second-quarter revenue. Shares of Facebook rose 1.4%, while Apple dipped 0.2%. Meanwhile, the U.S. central bank’s policy statement is expected to largely follow the mold established in December, when the Fed said it would not change monetary policy until there had been “substantial further progress” in meeting its maximum employment and 2% inflation goals. The statement is due at 2 p.m. EDT. “Investors will get what they are expecting, which is continued super dovish comments from the Fed,” said Christopher Grisanti, chief equity strategist at MAI Capital Management in Cleveland. “If there is any change from that stand, it’ll be a big deal for the markets, but that is unlikely.” At 10:10 a.m. ET the Dow Jones Industrial Average was down 148.57 points, or 0.44%, at 33,836.36, the S&P 500 was up 8.11 points, or 0.19%, at 4,194.83 and the Nasdaq Composite was up 18.24 points, or 0.13%, at 14,108.45. The tech-heavy Nasdaq on Monday completed a full recovery from its 11% correction that began in February, largely supported by a rise in mega-cap stocks and ebbing inflation fears. Microsoft Corp met quarterly sales expectations and beat profit estimates, but its shares fell 2.9% due to skepticism about one-off benefits included in the results and high hopes after a year-long rally. Biotech Amgen Inc’s 7.6% decline weighed on the Dow after it said its first-quarter sales and profit fell due to a 7% drop in its net drug prices and a hit from the COVID-19 pandemic. Boeing Co fell 3% after posting a wider-than-expected quarterly loss, even as it reported an improvement in aircraft deliveries as its 737 MAX jets come back on line. Overall earnings for S&P 500 companies in the first quarter are expected to jump 35% from a year earlier, which would be the biggest surge since the fourth quarter of 2010, according to Refinitiv IBES data. U.S. President Joe Biden is expected to unveil a sweeping $1.8 trillion package for families and education in his first joint speech to Congress, senior White House officials say. Advancing issues outnumbered decliners by a 1.12-to-1 ratio on the NYSE. Declining issues outnumbered advancers for a 1.19-to-1 ratio on the Nasdaq. The S&P index recorded 55 new 52-week highs and no new low, while the Nasdaq recorded 61 new highs and nine new lows. (Reporting by Shivani Kumaresan and Shreyashi Sanyal in Bengaluru; Editing by Anil D’Silva)