* Ceasefire deal reached between Ukraine, Russia
* Sweden introduces negative interest rates, bond buys
* Cisco up after results; Tesla falls
* Expedia to buy Orbitz; shares jump
* Indexes up: Dow 0.21 pct, S&P 0.46 pct, Nasdaq 0.65 pct (Updates to market open, adds data)
By Chuck Mikolajczak
NEW YORK, Feb 12 (Reuters) - U.S. stocks advanced early on Thursday, with the Nasdaq at a 15-year high, following a ceasefire agreement between Russia and Ukraine and surprising stimulus measures by Sweden's central bank, although soft economic data tempered gains.
Leaders of Germany, France, Russia and Ukraine agreed a deal to end fighting in eastern Ukraine, potentially removing a concern for investors, although the pact remained fragile.
Also helping to lift futures was a decision by Sweden's Riksbank to introduce negative interest rates and launch bond purchases, while saying it could take further steps to fight falling prices.
Talks over Greek debt with euro zone finance ministers failed to yield an agreement, with negotiations set to continue on Monday. Greek Prime Minister Alexis Tsipras was in Brussels on Thursday to lay out his case for more financial help to fellow EU leaders after the talks with finance ministers stalled.
Gains were curbed as data showed initial jobless claims rose more than expected in the latest week, while retail sales barely rebounded in January. In addition, business inventories rose less than expected in December, supporting views that fourth-quarter growth was slower than initially thought.
"You have all these sort of overseas positives and two domestic negatives with the claims data and the retail sales data missing," said Phil Orlando, chief equity market strategist at Federated Investors in New York.
"So we are still stuck in this trading range with a lot of volatility and nervousness."
The Dow Jones industrial average rose 37.64 points, or 0.21 percent, to 17,899.78, the S&P 500 gained 9.53 points, or 0.46 percent, to 2,078.06 and the Nasdaq Composite added 31.15 points, or 0.65 percent, to 4,832.34, its highest since March 2000.
Cisco Systems, which jumped 8.6 percent to $29.25 after the network equipment maker reported stronger-than-expected quarterly revenue and profit.
Tesla Motors dropped 7.7 percent to $196.29 after the electric-car maker missed fourth-quarter sales targets and analysts' profit expectations.
Orbitz Worldwide shares surged 21.3 percent to $11.67 after the online travel agency agreed to be acquired by Rival Expedia for about $1.38 billion. Shares of Expedia were up 11.8 percent at $87.48.
American Express shares dropped 6.2 percent to $80.71 as the biggest drag on the Dow after it said Costco Wholesale Corp would stop accepting its cards in the United States from next April, after the companies failed to reach terms on the renewal of an agreement. Costco shares edged down 0.4 percent to $146.89.
Advancing issues outnumbered declining ones on the NYSE by 2,110 to 602, for a 3.50-to-1 ratio on the upside; on the Nasdaq, 1,577 issues rose and 587 fell for a 2.69-to-1 ratio favoring advancers.
The benchmark S&P 500 index posted 34 new 52-week highs and no new lows; the Nasdaq Composite recorded 60 new highs and 4 new lows.
Editing by Bernadette Baum