World shares were in a cautious mood on Monday and Wall Street futures lay flat as stalled U.S. debt ceiling negotiations approached crunch time. U.S. President Joe Biden and House Republican Speaker Kevin McCarthy will meet to discuss the debt ceiling on Monday, less than two weeks before a June 1 deadline after which Treasury expects the federal government will struggle to pay its debts. A failure to lift the debt ceiling would trigger a default, likely sparking chaos in financial markets and a spike in interest rates. The MSCI All-World index was up 0.2% on the day, while Europe's…