Citigroup Inc (C.N) may have to a take a charge of almost $6 billion in the current quarter on a markdown of its valuation of the retail brokerage business it owns with Morgan Stanley (MS.N), Barclays Capital said.

The third-largest U.S. bank said last month that Morgan Stanley estimates the business, known as Morgan Stanley Smith Barney, is worth less than half as much Citi believes it is.

The disagreement came as Morgan Stanley tried to buy another 14 percent of the joint venture, beyond the 51 percent it owns.

Citi estimates the business is worth $22 billion, while Morgan Stanley pegs it at $9 billion.

                                        Citi CEO, Vikram Pandit

The bank’s valuation reflected an extremely optimistic view of the future of Wall Street profits, setting up the possibility of a multi-billion charge.

Read More: Reuters