Microsoft (MSFT) partner OpenAI has received a $10 billion investment from SoftBank, completing the investor's acquisition of a 13% equity stake in the AI-modeler, SoftBank said Thursday.

The Japan-based financial house has executed the third, final tranche of a total $30 billion in follow-in investments into the privately-held OpenAI, and has completed a cumulative total of $64.6 billion of investments into OpenAI, SoftBank said.

The latest $10 billion tranche was funded by the issue of $11.1 billion foreign currency-denominated senior notes, as disclosed last week, SoftBank said.

On Sept. 30, SoftBank canceled the remaining $10 billion of undrawn capacity under a $40 billion bridge facility agreement that had been entered into in March, the company said.

Following the cancellation, and upon the early repayment of bridge loan, all borrowings under the bridge facility have been repaid, and no undrawn commitments remain, SoftBank said.