Abiomed Inc. will join the S&P 500 index replacing Wyndham Worldwide Corp. S&P Dow Jones Indices said late Friday. The Danvers, Mass. based medical device company is expected to move to the S&P 500 before the opening of trading on May 31 as it is more representative of the index than Wyndham, S&P said. Shares of Abiomed declined 2.9% after hours, following a 0.1% decline to close the regular session at $394.28.