NEW YORK (CNNMoney) -- U.S. stocks were set to extend gains Tuesday, following world markets higher, as investors awaited a confidence vote for Greek Prime Minister George Papandreou.
Dow Jones industrial average (), S&P 500 ( ) and Nasdaq ( ) futures were about 0.5% higher ahead of the opening bell. Futures measure current index values against perceived future performance.
The vote of confidence, held by the Greek parliament, may determine whether Papandreou's government has the strength to avoid a default and secure a rescue package.
Despite ongoing anti-government protests, investors are largely expecting Papandreou to win the vote, said Mark Luschini, chief investment strategist, Janney Montgomery Scott.
"What Greece doesn't need at the moment is a complete turnover in its cabinet, so [Papandreou] is asking the people to give him a vote of confidence that he is doing the right thing," Luschini said. "And the people don't have much of a choice -- they don't want some of the austerity measures, but their country isn't going to be lent money without being willing to demonstrate it can get its fiscal house in order."
But any rally that comes out of Tuesday's vote is likely to be short-lived, Luschini said.
"We could have a relief rally that this lingering issue may be put to bed for the time being, but it doesn't remove the other headwinds that the market is still grappling with," he said. "We're still dealing with mushy economic data on a global basis."
U.S. stocks managed gains Monday, even as investors remained cautious about Greece's debt crisis.
But those gains were limited as investors grappled with the latest news on Greece. European finance ministers said Monday that the country won't receive fresh loans until mid-July.
World markets: European stocks were also higher ahead of the vote. Britain's FTSE 100 rose 0.9%, the DAX in Germany jumped 0.9% and France's CAC 40 added 1.3%.
Asian markets ended the session higher. The Shanghai Composite climbed nearly 1%, the Hang Seng in Hong Kong gained 1.2% and Japan's Nikkei rose 1.1%.
Economy: Wall Street will get May existing home sales data from the National Association of Realtors at 10 a.m. ET. Economists surveyed by Briefing.com expect the pace of existing home buying to slow to 4.79 million annualized units, down from 5.05 million units in April.
The Federal Reserve Open Market Committee starts its two-day meeting Tuesday. The central bank's interest rate decision will be announced on Wednesday.
Companies: Credit union regulators sued JPMorgan ( , Fortune 500) and Royal Bank of Scotland ( ) for selling mortgage bonds that were designed to fail -- leading federal credit unions to lose more than $800 million. Shares of JPMorgan rose 0.8%, while Royal Bank of Scotland's stock edged lower.
Shares of Bed Bath & Beyond (Fortune 500) jumped more than 4% after Jefferies reaffirmed its "buy" rating and $62 price target for the company's stock -- expecting Bed Bath & Beyond to beat earnings estimates in the first quarter.,
Best Buy Inc. (Fortune 500)'s board authorized a new $5 billion share repurchase program to replace its previous $5.5 billion share repurchase program. Shares of the company rose 4.3% in premarket trading.,
Shares of Renren () gained 2.5% before the market open, after the Chinese social-networking site reported a narrower loss in the first quarter, as sales increased 47%.
Drugstore chain Walgreens (Fortune 500) reported third-quarter results before the opening bell that beat expectations, posting record earnings and revenue.,
Separately, the company announced that contract renewal negotiations with pharmacy benefit manager Express Scripts have been unsuccessful, so it will no longer fill prescriptions using Express Scripts beginning in 2012. Shares of Walgreens fell 5% in premarket trading, while shares of Express Scripts slid 4%.
Bookseller Barnes & Noble (Fortune 500) and will also report before the market open on Tuesday. Media software giant Adobe ( ) will release results its quarterly earnings after the close.
Analysts expect Barnes & Noble to post a loss of 91 cents a share, according to Thomson Reuters. Adobe is expected to earn 51 cents a share.
Oil for July delivery gained $1.08 to $94.34 a barrel.
Gold futures for August delivery rose $3.10 to $1,545.10 an ounce.
Bonds: The price on the benchmark 10-year U.S. Treasury edged lower, pushing the yield up to 2.98% from 2.96% late Monday.
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