Japanese stocks have been battered so badly that they're too cheap to ignore, says the $165 billion investor Pictet Asset Management Ltd., after the Topix index tumbled to its fifth straight weekly loss.

"It's a buying opportunity," Hiroshi Matsumoto, head of Japan investment at the money manager, said in a phone interview from Tokyo.

Matsumoto gave two reasons why he's bullish: The market is undervalued because investors are overly pessimistic about the next round of quarterly earnings starting in two weeks, and about the risks associated with North Korea. Once people realize they're being too negative, Tokyo stocks should rise, he said.