NEW YORK (Reuters) - Investors pulled out of U.S. corporate bonds on Wednesday as the three major stock indexes sold off on reports of higher COVID-19 cases worldwide and on nerves about next week’s U.S. presidential election.Markit’s North American High-Yield CDX Index - which tracks the cost to insure high-yield corporate debt and is a proxy for the junk market - fell in price to 103.695%, the lowest since Sept. 28, as investors sold the contract betting on credit deterioration. Spreads on Markit’s North American Investment Grade CDX Index widened as far as 63.84 basis points, the highest since Sept. 18, as investors there also bet on a rise in defaults. Credit markets were moving in step with Wall Street’s main indexes which briefly lost more than 3% as new cases and hospitalizations set records in the U.S. Midwest, while concerns about shutdowns in France and Germany sapped investor appetite for risk.