Berkshire Hathaway said it bought more than $4.1 billion of stock in Taiwan Semiconductor Manufacturing, a rare significant foray into the technology sector by billionaire Warren Buffett’s conglomerate.

The news sent shares in TSMC soaring, closing up 7.9% in Taiwan on Tuesday, as it boosted investor sentiment for the world’s largest contract chipmaker, which saw its shares hit a two-year low last month due to a sharp slowdown in global chip demand.

In a Monday regulatory filing describing its U.S.-listed equity investments as of Sept. 30, Berkshire said it owned about 60.1 million American depositary shares of TSMC.

TSMC’s other foreign investors include U.S. asset managers BlackRock Inc and Vanguard Group Inc, and Singapore sovereign wealth fund GIC.

Berkshire also disclosed new stakes of $297 million in building materials company Louisiana-Pacific Corp and $13 million in Jefferies Financial Group Inc. It exited an investment in Store Capital Corp, a real estate company that agreed in September to be taken private.