* U.S. data shows jobs cut slow in May

* IMF's Lipsky says worst past

* Wal-Mart announces $15 bln stock buyback

* Bank of Japan mulling better outlook - sources

* Rio Tinto drops plans for tie-up with China's Chinalco

(For more on the global crisis, click [nCRISIS])

By Lewis Krauskopf and Tom Bergin

NEW YORK/LONDON, June 5 (Reuters) - U.S. employers last month cut the fewest jobs since September and international policy-makers said the worst of the downturn may be over as more positive corporate news popped up around the globe.

Data showing U.S. nonfarm payrolls fell by 345,000 in May came amid optimistic signals from the International Monetary Fund and the Bank of Japan.