The S&P 500 index rose five points, or 0.3 percent, to 1,801.46 as of 12:02 p.m. (1702 GMT). The Dow Jones industrial average gained 18 points, or 0.1 percent, to 16,024 in early trading. The Nasdaq composite gained 18 points, or 0.4 percent, to 3,987.
Biogen rose $31.33, or 13 percent, to $283.85. Time Warner gained $10.52, or 9 percent, to $131.35.
The S&P 500 has gained 26.2 percent this year. If it finishes at that level, it will be the strongest year for the index since it advanced 26.4 percent a decade ago.
Given the strong gains this year, stocks are no longer a bargain. Good news in the drug industry is pushing the U.S. stock market deeper into record territory, AP reported.
Health care stocks led the market's gains. Biotechnology company BioGen surged on reports that it won market exclusivity for its top-selling multiple sclerosis drug in Europe. Time Warner Cable jumped after the Wall Street Journal reported that Charter Communications was close to a bid for the company.
The stock market is on track for its best year in a decade. Major indexes have surged as a combination of solid corporate earnings, a strengthening economy and easy-money policies from the Federal Reserve have drawn investors to stocks.
The price-earnings ratio of S&P 500 companies, a measure of how much investors are willing to pay for a stock in relation to its earnings, has climbed to 14.9 from 12.6 at the start of the year.