With a little over 24 hours to go before the deadline for acceptances, investors remain cautious about whether Greece will attract enough investor support for a deal meant to head off a messy default.
In recent days, investors have also been worried about global growth, especially in light of the recent rise in oil prices. Another positive US jobs survey Wednesday helped shore up markets despite a surprise drop in German industrial orders and weaker than anticipated Australian economic growth.
But analysts warned that the rally in shares could be short-lived since worries over Greece remain — and not just in the short term.
"It is perfectly possible that the euro zone and Greece could find themselves in three years time in exactly the same spot they were in at the start of this year," said Simon Derrick, an analyst with Bank of New York Mellon. "Whether the political will for such a top-up would be there by 2015 of course remains very much open to question. Little wonder then that the issue of a euro zone exit should remain very much on the agenda."
More imminently, Thursday marks the last day the country's private creditors can sign up to a deal meant to slash 107 billion euros ($140 billion) off Athens' books and hopefully put it on the path to recovery.
The creditors will take hefty losses if they agree to swap their bonds, but European leaders have painted the deal as the only way to prevent a messy Greek default that would have widespread repercussions for banks and economies throughout the 17-country euro zone.
Private creditors have been asked to swap their bonds for new ones with a face value that is 53 percent lower and with longer maturities and lower interest rates. Some creditors, including hedge funds, are thought to be weighing up the benefits of holding out for a potentially bigger insurance return, though a trickle of investors announced Wednesday they would sign up to the plan.
If the takeup is below 90 percent, but still above the crucial 66 percent threshold for the deal to go ahead, the Greek government could force holdouts to accept the swap. That may be considered a credit event — a technical term for a default — meaning bond insurers would have to pay the Greek bondholders.
Worries over the swap sent stocks tumbling this week, including a more than 200-point drop in the Dow Jones industrial average on Tuesday, that ended a streak of calm.
But on Wednesday, stocks rose, partially boosted by ADP's report that the US economy added 216,000 jobs last month. That figure, while solid, was largely in line with analyst expectations so the advance was capped.
In Europe, the French CAC-40 ended 0.9 percent higher at 3,392, while Germany's DAX rose 0.6 percent to 6,671. The FTSE index of leading British gained 0.4 percent to 5,791.41. The euro edged up to $1.3148.
Wall Street was also higher. The Dow Jones Industrial Average gained 0.6 percent to 12,832, while the broader Standard & Poor's index rose the same rate to 1,352.
Investors are also worried about oil prices, which have been charging up amid unrest in Syria and Libya and tensions between Israel and Iran. The concern is that inflated energy prices could weigh on any economic rebound.
Benchmark oil for April delivery was up 94 cents to $105.66 per barrel in electronic trading on the New York Mercantile Exchange.
Earlier Asian markets were lower as they weighed these fears.
Japan's Nikkei 225 index fell 0.6 percent to close at 9,576.06, while Hong Kong's Hang Seng slid 0.9 percent to 20,627.78. South Korea's Kospi lost 0.9 percent to 1,982.15. Benchmarks in Australia, Taiwan, Singapore and Indonesia also fell.
In mainland China, the benchmark Shanghai Composite Index lost 0.7 percent to 2,394.79. The Shenzhen Composite Index for China's second, smaller exchange lost 0.5 percent to 967.05.
