Only 30 S&P 500 stocks are gaining, as health care stocks lead the losers

With the S&P 500 (S&P:SPX) tumbling 2.2%, toward the biggest one-day selloff in about seven weeks, only 30 of the index's components are trading higher. The biggest gainer is SVB Financial Group's stock , which rallied 10.7% after the banking company reported late Thursday first-quarter profit and revenue that beat expectations. The next biggest gainer was Kimberly-Clark Corp.'s stock (NYS:KMB) , which jumped 9.2%, after the consumer products company beat earnings expectations and raised its guidance. Meanwhile, biggest losers were all in the health care sector, with shares of HCA Healthcare Inc. (NYS:HCA) tumbling 18.9%, Intuitive Surgical Inc. (NAS:ISRG) falling 13.5%, Universal Health Services Inc. (NYS:UHS) losing 12.5% and DaVita Inc. (NYS:DVA) dropping 8.9%.