By Devik Jain and Bansari Mayur Kamdar Jan 28 (Reuters) - The S&P 500 index was closing in on a correction on Friday for the fifth time this week on worries about a series of interest rate hikes to tame inflation and losses in shares of Caterpillar and Chevron. Caterpillar Inc CAT.N fell 4.8% after the world's largest heavy-duty equipment maker warned of margin pressure from higher production and labor costs. Meanwhile, data showed core personal consumption expenditure price index, the Federal Reserve's preferred gauge for inflation, rose 0.5% in December, in line with expectations.