Merrill Lynch & Co., the securities firm acquired by Bank of America in 2009, made the original investment in HCA for about $1 billion in 2006, Dubrowski tells Bloomberg. Counting the latest sale, dividends, and an initial public offering, BofA had $3 billion in proceeds from that investment.

Bank of America gained 13 cents, or 1.8 percent, to $7.18 at 9:40 a.m. in New York Stock Exchange composite trading. HCA surged $1.86 to $20.47.

The Citigroup plan will apply to its trading and investment-banking units worldwide as well as consumer banking and global transaction services, Shannon Bell, a spokeswoman for the New York-based bank, tells Bloomberg. The bank had 263,000 employees at the end of the second quarter.

CEO Vikram Pandit, seeing weaker consumer confidence and the prospect of high unemployment continuing, wants to control costs.

And in that environment, the bank has "ongoing efforts to tightly manage expenses [and is] currently only filling positions we believe are critical to the line of business or function," according to Bell.