Japanese activist investor Yoshiaki Murakami is building a stake in semiconductor manufacturer NuFlare Technology Inc., potentially complicating Toshiba Corp.'s plan to take full ownership of the company, Reuters reported.

Toshiba, which currently owns 52.4% of NuFlare, announced tender offers last month to fully acquire the company along with two other subsidiaries, Nishishiba Electric Co. Ltd. and Toshiba Plant Systems & Services Corp., for a total of ¥200 billion.

Murakami, who has resurfaced after being convicted of insider trading in 2007, has built a 6.2% stake in NuFlare since Toshiba announced its buyout plans, Reuters reported, citing regulatory filings.

NuFlare's second-largest shareholder Toshiba Machine Co. Ltd., in which Toshiba holds a 2% stake, has still not decided whether to endorse the tender offer. Funds backed by Murakami are Toshiba Machine's largest shareholder with a 9.2% stake.

A Toshiba spokesperson said the company has no intention of changing the terms of its offer, Reuters said.

As of Dec. 9, US$1 was equivalent to ¥108.60.