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* Fed leaves rates unchanged, promised more support

* Starbucks sees business 'steadily recovering', shares up

* Boeing falls after bigger-than-expected loss

* Advanced Micro Devices surges after revenue forecast raise

* Indexes up: Dow 0.4%, S&P 1.02%, Nasdaq 1.2% (New throughout, updates prices, market activity and comments to late afternoon; new byline, adds NEW YORK dateline)

New York, July 29 (Reuters) - U.S. stocks added to gains on Wednesday after the U.S. Federal Reserve repeated a pledge to use its "full range of tools" to support the economy for as long as it takes to recover from fallout of the pandemic.

At the end of its two-day policy meeting the Fed said it maintained its interest rate target range until it is confident the economy has weathered the virus and is on track to achieve its maximum employment and price stability goals.

"This was pretty much as expected. The key statement will be in September when they give some forward guidance,” said Stan Shipley, Evercore ISI macro research analyst in New York.

Wall Street's major indexes were already higher before the Fed commentary, on the eve of scheduled earnings reports from Amazon.com Inc, Facebook Inc, Apple Inc and Alphabet's Google. The chief executives of all four companies also faced a congressional hearing on antitrust issues.

"You'll often see an uptick in those shares ahead of earnings and if they disappoint then they tend to sell off," said Shawn Snyder, head of investment strategy at Citi Personal Wealth Management.

At 2:30 p.m. ET (1830 GMT), the Dow Jones Industrial Average rose 105.68 points, or 0.4%, to 26,484.96, the S&P 500 gained 32.98 points, or 1.02%, to 3,251.42 and the Nasdaq Composite added 124.98 points, or 1.2%, to 10,527.07.

All 11 major S&P sectors were higher with financial and technology stocks leading the percentage gainers.

Investors were also focused on contentious negotiations in Washington around what should go into government's next coronavirus relief plan days before enhanced unemployment benefits were set to expire.

On Tuesday, U.S. President Donald Trump said he did not support everything in a Senate Republican proposal but would not elaborate.

Advanced Micro Devices Inc shares were up 12.6% after the chipmaker raised its full-year revenue forecast and the Philadelphia chip index rose 2%.

Starbucks Corp climbed 4% after the coffee chain said business was "steadily recovering" worldwide and it would report a profit in the current quarter.

Of the S&P 500 firms that have reported results, 79.1% have surpassed a low bar of quarterly profit expectations, according to Refinitiv IBES data.

Recent data pointed to a possible slowdown in business and hiring as several U.S. states reimposed restrictions after a spike in COVID-19 infections, while deaths in the country caused by the disease surpassed 150,000 on Wednesday.

Boeing Co slipped 2.6% as it slashed production on its widebody programs and reported a bigger-than-expected loss due to the fallout from the pandemic.

Advancing issues outnumbered declining ones on the NYSE by a 3.18-to-1 ratio; on Nasdaq, a 1.92-to-1 ratio favored advancers.

The S&P 500 posted 37 new 52-week highs and no new lows; the Nasdaq Composite recorded 73 new highs and 14 new lows. (Additional reporting by Ross Kerber in Boston, Medha Singh and Devik Jain in Bengaluru; Editing by Shounak Dasgupta and David Gregorio)