* 10-year U.S. yields drop under 2-yr 1st time in 12 years
* Markets fear inversion heralds recession, hope for Fed rescue
* Oil extends big overnight drop on demand, supply pressures (updates throughout, changes byline, dateline)
By Sujata Rao
LONDON, Aug 15 (Reuters) - World shares held at 2-1/2-month lows on Thursday and Wall Street was set for a firmer open as investors bet the U.S. Federal Reserve and other central banks would respond strongly to recession warnings emanating from bond markets.
European shares opened higher and futures flagged a 0.5% rise on Wall Street, where all three indexes fell 3% on Wednesday after an inversion of U.S. government bond yields sparked fears that the world's biggest economy would hurtle towards recession, dragging the rest of the globe with it.
Yields on 10-year Treasury bonds dropped below shorter two-year rates for the first time in 12 years, when the same the yield curve inversion presaged the 2008 recession.
The curve has inverted before every recession in the past 50 years, offering a false signal just once in that time
The latest inversion has since reversed, albeit marginally, and yields on 30-year Treasuries rose off the record 1.965% low hit in Asian trading. But they are still down 60 basis points in just 12 sessions.
Meanwhile German 30-year yields are below minus 0.2% for the first time, while 10-year yields touched an all-time low of minus 0.665% before inching higher.
A pan-European equity index opened marginally firmer while S&P500 futures rose 0.6%. Asian shares however fell 0.5%, with Japan's Nikkei shedding 1.2% as the recent yen surge hit the export-heavy bourse.
MSCI's world equity index was down 0.2%, attempting to steady after the previous day's 2% rout.
Markets appear to be pinning their hopes, yet again, on central banks, betting that scale of the scare would alarm policymakers, especially at the Fed.
"The only game in town is the central banks," said Peter Schaffrik, global macro strategist at RBC Capital Markets
Economic stress in Argentina, fears of Chinese military intervention in Hong Kong and trade tensions worldwide are all pressuring the economic outlook, analysts note.
"You have a lot of forces that weigh on the global economy which doesn't really mean it needs to be a recession. The only policy response is from central banks, hence the market is rallying," Schaffrik added.
Money markets price a growing chance the Fed will cut rates by half a point at its September meeting.
"Hoping for the best on the policy front but positioning for the worst on the economic backdrop seems to be the flavour of the day," said Stephen Innes, a managing partner at Valour Markets.
"The Fed, now out of necessity alone, will need to adjust policy much more profoundly than they expected."
Moreover, not everyone buys the argument that recession is inevitable, given that bond markets have been distorted by a decade of multi-trillion dollar central bank stimulus.
Mark Haefele, chief investment officer at UBS Global Wealth Management said how long the curve remained inverted, and to what extent, was crucial.
"If Fed rate cuts successfully steepen the curve comfortably into positive territory, this brief curve inversion may be a premature recession signal. Neither does a yield curve inversion indicate it is time to sell equities," Haefele said.
He noted that since 1975, every curve inversion had been followed by an S&P500 rally which lasted almost two years and delivered gains of around 40% on average.
Global growth concerns have mounted as the Sino-U.S. trade war escalated, and what sent the curve over the brink was German data on Wednesday showing the economy had contracted in the quarter to June. That came on the heels of dire Chinese data for July.
These concerns have sent oil prices plunging with Brent crude losing another 0.5% to $59.16 a barrel, after shedding 3% overnight.
Gold has surged to six-year highs, benefiting, like bonds, from investors' need for safe-haven assets. It dipped on Wednesday by 0.2% to $1,512 per ounce but stayed near its recent $1,534 high.
The yen too pulled back 0.3%, having firmed for eight of the past ten sessions against the dollar. Excluding a mini-crash episode in January, it recently hit 17-month highs .
The dollar index was a shade easier at 97.925, with the under-pressure euro at $1.1149 following Wednesday's soft German data.
Mizuho senior economist Colin Asher forecast more yen strength.
"Regardless of the type of slowdown in the US, it will be bad news for the Japanese economy as one of its major trading partners heads for slower growth," he said. "This is likely to be negative for asset markets and boost demand for the yen."
Additional reporting by Tomo Uetake, Wayne Cole and Virginia Furness; ; editing by John Stonestreet