Oct 13 (Reuters) - AvidXchange Inc opened around 3.4% below its initial public offering price in its Nasdaq debut on Wednesday, giving the U.S. business payments firm a market capitalization of roughly $4.62 billion. Shares of the company, which counts Mastercard Inc among its investors, opened at $24.14, compared with the IPO price of $25 per share. (Reporting by Sohini Podder in Bengaluru; editing by Uttaresh.V) Our Standards: The Thomson Reuters Trust Principles.