Megmilk Snow Brand Co., Japan's third-largest milk producer, surged by a record in Tokyo trading Monday on speculation China's Hangzhou Wahaha Group Co. may buy a stake. Megmilk said it isn't in talks with Wahaha.

The Sapporo-based firm rose as much as 6.5 percent to ¥1,567 on the Tokyo Stock Exchange, the biggest intraday gain since it sold shares in October 2009, and closed at ¥1,505, up 2.31 percent from the previous day.

A Japanese yogurt maker recently approached Wahaha, China's third-biggest soft-drinks maker, about acquiring it, Hangzhou Wahaha Group Chairman Zong Qinghou, China's richest man, said at a Sunday briefing in Beijing. Talks haven't started, he said, without giving more details.