NEW YORK, Aug 25 (Reuters) - Wall Street gained ground on Wednesday, with chipmakers and financials helping to push the S&P 500 and the Nasdaq to record closing highs as investors look to the upcoming Jackson Hole Symposium for assurances that Federal Reserve"s timeline for policy tightening remains intact. With few negative catalysts to sour the risk-on sentiment, all three major U.S. indexes ended the session modestly higher. "Positive news on vaccination approvals, and expectations that the Fed won’t shock markets at Jackson Hole, are helping to keep equity prices higher," said David Carter, chief investment officer at Lenox Wealth Advisors in New York, who added "it"s a very quiet market as many investors are sitting on the beach this week." Rising U.S. Treasury yields boosted rate sensitive financials (.SPSY), and sectors that stand to gain most from economic revival - smallcaps (.RUT), chips (.SOX) and transports (.DJT) - were outperforming the broader market. Days after the Food and Drug Administration gave full approval to the Pfizer-BioNTech COVID-19 vaccine, companies and institutions are moving toward either mandated inoculation, or penalization for those who forego the shot. The Pentagon and Delta Air Lines (DAL.N) are the latest to enact such measures, with Ford Motor Co (F.N) and others potentially following suit. read more For an interactive graphic on global vaccine deployment and new infection rates, click here. Analysts polled by Reuters see the stock market staying rangebound for the remainder of 2021, with the S&P 500 ending the year little changed as the pandemic recovery, along with corporate earnings growth, lose steam. read more"Following a long run, equity indexes have cooled off as the next engine of growth is unclear," Carter at Lenox Wealth Advisors added. "Fiscal and monetary stimulus may have lost their oomph to push markets higher still." Tame economic data, including flat new orders for core capital goods read more , reinforced the notion that Fed Chairman Jerome Powell is unlikely to hint at a shortened timeline for policy tightening at the virtual Jackson Hole Symposium, due to get underway on Friday. "(The) expectation is that Fed won"t scare markets, and will announce only a cautious tapering," Carter said. Unofficially, the Dow Jones Industrial Average (.DJI) rose 42.1 points, or 0.12%, to 35,408.36, the S&P 500 (.SPX) gained 10.01 points, or 0.22%, to 4,496.24 and the Nasdaq Composite (.IXIC) added 22.68 points, or 0.15%, to 15,042.48. Financials were the clear winners among 11 major sectors in the S&P 500, gaining more than 1%. Healthcare stocks (.SPXHC) suffered the largest percentage decline. Chipmakers Nvidia Corp (NVDA.O) and Applied Materials (AMAT.O), along with mega-cap growth stocks Alphabet Inc (GOOGL.O), Tesla Inc (TSLA.O) and Facebook Inc (FB.O), provided the biggest boost to the Nasdaq. Nordstrom Inc (JWN.N) tumbled after the department store operator posted a 6% decline in quarterly revenue from pre-pandemic levels. read more Dick"s Sporting Goods Inc (DKS.N) announced a special dividend and raised its annual sales and profit forecast, sending its shares surging.