Legg Mason is being bumped from the S&P 500, the stock market index that includes the 500 largest companies by market capitalization.
After markets close Thursday, the Baltimore money manager will be replaced by AmSurg Corp., a Tennessee health care company that is expected to finalize its acquisition of another health care firm earlier in the day, boosting its market capitalization.
Legg Mason will take AmSurg's spot on the S&P MidCap 400.
"We continue to believe in what we're doing and will continue to manage our business as usual," said Mary Athridge, a spokeswoman for Legg Mason. "It doesn't change what we're doing."
Legg Mason's stock closed up 2 percent, at $31.90 a share, in Wednesday trading.
With a market capitalization of about $3.2 billion, Legg Mason was ranked near the bottom of the S&P 500 and was more representative of a mid-cap company, S&P Dow Jones Indices said in a statement announcing the change.
S&P's indexes are organized by market capitalization, which is a calculation based on the price of a company's stock and the number of outstanding shares.
Legg Mason's market capitalization has dropped about 23 percent, from $4.16 billion, since the beginning of the year, as the company bought back more stock and its stock price fell. Legg shares are down nearly 19 percent since Jan. 1.
Still, the move is not expected to have a material impact on investors' long-term outlook for Legg Mason, said Macrae Sykes, an analyst at Gabelli & Co. in Rye, N.Y.
"I don't think it's a big deal," Sykes said. "It doesn't affect the fundamental outlook for the company."
Baltimore companies still among the S&P 500 include T. Rowe Price Group Inc., Under Armour and McCormick & Co.