* ECB cuts rates, to buy asset-backed securities
* BP shares slump after court ruling
* ADP payrolls short of estimates, initial claims up
* Ciena stumbles after results, outlook
* Indexes up: Dow 0.23 pct, S&P 0.26 pct, Nasdaq 0.33 pct (Updates to afternoon, adds new comments, details on BP)
By Akane Otani
NEW YORK, Sept 4 (Reuters) - U.S. stocks climbed on Thursday after the European Central Bank cut interest rates and announced a new plan to stimulate the euro zone economy, and as a flurry of data pointed to a steadily improving U.S. economy.
Both the Dow and S&P 500 touched record intraday highs after the ECB's surprise move, with the benchmark index hitting a high of 2,011.17. Investors had hoped for decisive action from the ECB to thwart deflation and spur stagnating growth in the euro zone, a key trading partner of the U.S.
"The last time the ECB president made such a strong statement back in 2012, when he said he would take whatever action necessary to support the economy, it stabilized risk assets across the globe. I think this is a very similar moment," said Anwiti Bahuguna, senior portfolio manager for Columbia Management in Boston.
U.S.-listed shares of BP Plc fell 4.9 percent to $45.38 after a U.S. district judge ruled the company was "grossly negligent" for its role in a massive oil spill in the Gulf of Mexico in 2010. About $8.8 billion was wiped off BP's market value Thursday as the stock suffered its worst percentage decline since June 2012.
Shares of Apple were up 0.6 percent at $99.50. The stock had tumbled 4.2 percent a day earlier in the wake of news of a security beach of its iCloud service.
The Dow Jones industrial average rose 39.85 points, or 0.23 percent, to 17,118.13. The S&P 500 was up 5.18 points, or 0.26 percent, to 2,005.9. The Nasdaq Composite added 15.19 points, or 0.33 percent, to 4,587.75.
Data showed U.S. initial jobless claims rose to 302,000 last week, within levels consistent with a strengthening labor market, while U.S. companies hired fewer workers than expected in August, according to the private ADP survey. The U.S. Labor Department will release the widely watched monthly jobs report on Friday.
A separate report showed the U.S. trade deficit narrowed July to its lowest point in six months. Meanwhile, growth in the U.S. services sector rose in August to its best level since 2005.
Tibco Software rose 5 percent to $22.10 after the business software maker formed a special committee to find ways to boost shareholder value.
Ciena Corp shares dropped 7.6 percent to $18.91 after the network equipment company posted third-quarter results and provided its fourth-quarter outlook. (Editing by Bernadette Baum)