Letting a cyber threat data sharing law expire could waste government efforts to find vulnerabilities, since companies would no longer be able to discuss these issues without fear of legal repercussions, a top senator said Tuesday. Sen. Mike Rounds, R-S.D., made his remarks less than a week after the hotly contested legislation to end a government shutdown also temporarily extended the Cybersecurity Information Sharing Act of 2015 through the end of January. But the discussion from Rounds and