Insurer Ace Replaces Millipore on S&P 500

Standard & Poor’s Thursday said it will add property and casualty insurer Ace Ltd to its flagship Standard & Poor’s 500 stock index after the close of trading on July 14.

Ace will replace Millipore Corp, a maker of laboratory water filters and purifiers and other materials used to produce biotechnology drugs. Millipore is being acquired by Germany’s Merck KGaA in a transaction expected to close around July 14, S&P said.

Shares of companies joining the S&P 500 often rise after their inclusion is announced because many investors track the index and must buy shares of companies that enter it.

Ace shares rose $2.58, or 4.9 percent, to $54.80 within minutes of the S&P announcement after market hours. Shares of the Zurich-based company closed regular trading up 33 cents, or 0.6 percent, at $52.22 on the New York Stock Exchange.

(Reporting by Jonathan Stempel; editing by Carol Bishopric)