(For a live blog on the U.S. stock market, click or type LIVE/ in a news window.) * Microsoft, Apple biggest boost to S&P 500 and Nasdaq * Bristol-Myers Squibb rises as FDA approves cancer drug * Indexes up: Dow 0.76%, S&P 0.79%, Nasdaq 1% (Updates to midday) Aug 20 (Reuters) - Wall Street’s main indexes rose on Friday, boosted by tech stocks in a broad-based rally, although concerns over a slowing economic recovery and the possible tapering of stimulus saw the indexes on course for weekly losses. Facebook Inc, Apple Inc, Google-owner Alphabet Inc, Nvidia Corp, Tesla Inc and Microsoft Corp which had led Wall Street’s record rally from pandemic lows last year, gained between 0.7% and 3.5%. Global equities took a backseat this week, with U.S. stocks slipping from record highs as a rapid rise in coronavirus cases globally added to concerns about downbeat Chinese economic data and the outlook for U.S. stimulus. The Federal Reserve’s annual research conference in Jackson Hole, Wyoming, next week will be closely watched after minutes from the central bank’s last policy meeting showed officials largely expect to reduce unprecedented stimulus measures. Technology, utilities and materials led gains on Friday, with all the 11 major S&P sectors trading higher. The S&P healthcare sector has gained nearly 1.9% so far this week, the most among the major sectors. Growth shares were also buttressed by U.S. Treasury yields, which were set to end the week lower on fears that the spread of COVID-19 variants would slow economic normalization. “This is a better environment for the tech stocks. The environment for tech on macro picture is probably brightening to some degree as the economy begins to show signs of growth, but at a slower pace,” said Robert Pavlik, senior portfolio manager at Dakota Wealth in Fairfield, Connecticut. “This market is still trying to feel its way around. There’s no directional leadership coming out of any particular group, aside from maybe the healthcare space.” Tech stocks are particularly sensitive to rising yields because their value rests heavily on future earnings, which are discounted more deeply when bond returns go up. At 12:43 a.m. ET, the Dow Jones Industrial Average was up 266.40 points, or 0.76%, at 35,160.52, the S&P 500 was up 34.59 points, or 0.79%, at 4,440.39, and the Nasdaq Composite was up 145.12 points, or 1.00%, at 14,686.91. For the week, the blue-chip Dow and the benchmark S&P 500 are down about 1% and 0.6% respectively, while the tech-heavy Nasdaq has fallen 0.9%, the most since July 30. Deere & Co fell 2.5% even after it beat Wall Street estimates for third-quarter revenue and lifted its full-year earnings forecast on strong demand for farm and construction equipment. Bristol-Myers Squibb rose 1.1% after the U.S. FDA approved the drugmaker’s blockbuster cancer drug, Opdivo, for patients with high-risk urothelial carcinoma. Advancing issues outnumbered decliners by a 2.63-to-1 ratio on the NYSE and by a 2.36-to-1 ratio on the Nasdaq. The S&P index recorded 42 new 52-week highs and no new low, while the Nasdaq recorded 46 new highs and 162 new lows. (Reporting by Devik Jain and Medha Singh in Bengaluru; Editing by Subhranshu Sahu, Maju Samuel and Aditya Soni) Our Standards: The Thomson Reuters Trust Principles.