Kohl's Corp KSS.N gained 7.9% after a group of activist investors nominated nine directors to the department store chain's board. By Gertrude Chavez-Dreyfuss NEW YORK, Feb 22 (Reuters) - The S&P 500 and Nasdaq fell on Monday as climbing Treasury yields and prospects of rising inflation triggered valuation concerns, hitting shares of high-flying growth companies. Largely upbeat fourth-quarter earnings had powered Wall Street's main indexes to record highs earlier last week, but the rally lost steam, in part due to fears of a potential snag in U.S. vaccination efforts and inflation concerns emanating from a raft of stimulus measures.