TOKYO, May 22 (Reuters) - S&P Global Ratings upgraded SoftBank Group Corp's long-term credit rating by one notch to BB+, saying the outlook was stable on expectations of the company's ability to stay relatively stable financially in the near term.

"Over the next one to two years, SoftBank Group is likely to continue to stabilise its investment income and improve the quality of its investment portfolio to a greater degree than we had forecast," S&P said in a statement, pointing to a recovery in global technology companies' stock prices.

The ratings agency a year ago cut the rating deeper into junk territory citing the Japanese tech investment giant's exposure to unlisted companies that it deemed susceptible, drawing criticism from the company. (Reporting by Chang-Ran Kim; Editing by Muralikumar Anantharaman)