NEW YORK (Associated Press) - Standard & Poor's said Thursday that credit card company Mastercard Inc. will replace insurer ACE Ltd. in the S&P 500 index on July 17.

Mastercard will also replace General Motors Corp. in the S&P 100. GM will continue to be a member of the S&P 500, the index said.

S&P said ACE is changing its place of incorporation to Switzerland, rendering it ineligible for inclusion in S&P indexes.

S&P also said Natus Medical Inc., a provider of medical devices for newborn care, will replace specialty packaging company Chesapeake Corp. in the S&P SmallCap 600 on July 15.

Chesapeake's market value does not meet the minimum for companies in the index, S&P said.