NEW YORK (TheStreet) -- American Express Co. (AXP) - Get Report stock is decreasing 0.41% to $55.13 in mid-morning trading on Monday after the New York City-based credit card company announced plans to sell its Costco (COST) co-branded credit card portfolio to Citibank, Citigroup's (C) consumer unit. 

Shares of Citigroup are down 0.89% to $39.13, while Costco stock is up 1.34% to $151.69 this morning.

Eligible Costco American Express accounts will be transferred to Citi when the transaction is completed in June.

Terms of the deal were not disclosed, but American Express expects to gain an estimated $1 billion from the sale.

"Given that the close is still several months away, and the card member borrowing and paydown trends are difficult to predict in this type of transition, the final gain could differ from the estimate," American Express said in a statement.

The U.S. partnership between American Express and Costco is set to expire at the end of March after the companies failed to reach an agreement on a new contract last year.

Separately, American Express has a "hold" rating and a letter grade of C at TheStreet Ratings because of the company's strengths, such as revenue growth, good cash flow from operations and reasonable valuation levels, and its weaknesses, including disappointing stock performance, deteriorating net income and generally higher debt management risk.

You can view the full analysis from the report here: AXP

TheStreet Ratings objectively rated this stock according to its "risk-adjusted" total return prospect over a 12-month investment horizon. Not based on the news in any given day, the rating may differ from Jim Cramer's view or that of this articles's author.

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