SoftBank is accelerating asset sales after its flagship Vision Fund unit booked nearly $50 billion in losses in just six months, but Chief Executive Masayoshi Son faces narrowing options and slumping valuations, analysts said.

Son said on Monday that he is in discussions to sell asset manager Fortress, without commenting on a valuation. SoftBank also raised $2.4 billion selling shares in T-Mobile U.S. during the latest quarter, while unloading a variety of other holdings.

But as valuations fall, easy options for raising cash are getting harder to come by.