Activist investor Dan Loeb has gone long on another Japanese company. This time it’s Softbank Corp (TYO:9984) (OTCMKTS:SFTBF). Several media outlets (including Business Insider) are reporting that he disclosed his stake in the Japanese mobile carrier at the Robin Hood Investors’ Conference today, citing Twitter users like @stockwhisperer because the conference is officially closed to the press.

Dan Loeb Third Point

Shares of Softbank rose about 4% in the U.S. after the revelation. The company’s shares are traded over the counter.

Dan Loeb versus Sony

Loeb is quite bullish on the Japanese economy. He has been in the news quite a bit for his activist push against Sony Corporation (NYSE:SNE) (TYO:6758). He wants the Japanese company to spin off its entertainment business, but Sony will have none of it. Loeb as of a few months ago, Loeb’s fund held about a 7% stake in Sony. He was also shorting the yen as of earlier this year. He said he took profits on the yen but didn’t made it clear whether he completely exited that short position.

Exchange rates because of a weak yen may have something to do with his interest in Japanese companies. He said earlier this month that Sony would keep benefiting from a weak yen. Softbank especially may have become an interest for him because it is based in Japan but has now moved into the U.S. market through a major acquisition.

Softbank acquires Sprint

Recently Softbank Corp (TYO:9984) (OTCMKTS:SFTBF) took a nice chunk of the U.S. mobile market when it acquired Sprint Corporation (NYSE:S). That acquisition came quickly after Sprint acquired Clearwire, further adding to the wireless spectrum Softbank has gained this year in the U.S.

Shares of Sprint Corporation (NYSE:S) also received a boost after it was revealed that Dan Loeb is long on Softbank. The company’s stock rose more than 2%.

What does Dan Loeb have in store for Softbank?

Now that Loeb has revealed his stake in Softbank, investors will be wondering what he wants to do with the company. He often goes activist on the companies he invests in. He’s been rather nice to management of Sony Corporation (NYSE:SNE) (TYO:6758) since the Japanese culture is so different from the U.S. culture. So it will be interesting to see what, if anything, he does with his stake in Softbank Corp (TYO:9984) (OTCMKTS:SFTBF).