TOKYO, May 9 (Reuters) - Japan's Nippon Telegraph and Telephone Corp said on Monday it would combine its overseas business operations with NTT Data Corp.

NTT plans to keep NTT Data listed, NTT President Jun Sawada told a news briefing, dampening speculation it would take the subsidiary private after NTT Data's shares surged as much as 17% earlier in the day.

In 2020, NTT launched Japan's largest-ever tender offer for the shares in its wireless carrier, NTT Docomo, that it did not already own. ($1 = 130.9700 yen) (Reporting by Shinji Kitamura and Sam Nussey; Editing by Christian Schmollinger and Kim Coghill)