* JPMorgan revenue beat boosts stock; other banks also up
* BoE leaves rate unchanged, but signals stimulus to come
* Yum rises on strength in key China business
* Indexes up: Dow 0.69 pct, S&P 0.58 pct, Nasdaq 0.58 pct (Updates to open)
By Yashaswini Swamynathan
July 14 (Reuters) - The S&P 500 and the Dow touched record highs at the open on Thursday, boosted by JPMorgan's strong results, which set an upbeat mood for big banks earnings and spurred a rally in financial stocks.
Wall Street's record-setting rally extended to the fourth day, even as the Bank of England surprised investors by leaving interest rates unchanged at 0.50 percent.
But, investors saw hope after the central bank signaled there would be a stimulus program in August, once the impact of Britain's decision to leave the European Union had been assessed.
JPMorgan, the biggest U.S. bank by assets, reported quarterly revenue rise that beat estimates by a large margin. The bank's shares rose 2.2 percent, while the S&P financial index's 1.15 percent gain led the gainers among the 10 major S&P sectors.
"The fact that is giving everyone hope is that JPMorgan's revenues were strong and that shows business is being done," said Kim Forrest, senior equity research analyst at Fort Pitt Capital Group in Pittsburgh.
At 9:37 a.m. ET (1337 GMT) the Dow Jones industrial average was up 125.94 points, or 0.69 percent, at 18,498.06.
The S&P 500 was up 12.57 points, or 0.58 percent, at 2,165.
The Nasdaq Composite was up 28.92 points, or 0.58 percent, at 5,034.65.
"... It is the very beginning of earnings season and we will have wait and see what companies have to say about the future," said Forrest.
Citigroup and Wells Fargo are scheduled to report results on Friday. As the earnings season gathers steam, investors will parse reports to justify stock valuations.
Second-quarter S&P 500 earnings are expected to fall 5 percent, mirroring the first quarter. But analysts expect steady growth throughout the rest of the year, according to StarMine.
KFC owner Yum Brands rose 4.6 percent to $89.76 after its key China business showed signs of strength.
A host of Fed officials, including presidents of Atlanta and Kansas Feds, are scheduled to speak at separate events on Thursday. In recent speeches, many Fed authorities have called for no urgency in raising rates.
Advancing issues outnumbered decliners on the NYSE by 2,099 to 578. On the Nasdaq, 1,650 issues rose and 596 fell.
The S&P 500 index showed 57 new 52-week highs and no new lows, while the Nasdaq recorded 74 new highs and five new lows. (Reporting by Yashaswini Swamynathan in Bengaluru; Editing by Savio D'Souza)