Such index changes require fund managers whose investments track the S&P 500 to reallocate their holdings, including buying shares of stocks being added to the benchmark index.
Spectra is leaving the S&P 500 given its pending acquisition by Canada-based Enbridge, an oil and gas pipeline operator, the release said. U.S.-listed shares of Enbridge were 1 percent lower Friday, while Spectra traded little more than 0.5 percent lower.
Incyte specializes in oncology products and will be added to the S&P 500's biotechnology sub-industry index, according to the release.
Incyte shares hit a 52-week high Friday and are up about 30 percent for the year so far.