NEW YORK—The Securities and Exchange Commission charged Medallion Financial Corp. and its president with fraud for trying to inflate the stock price of the lender to taxicab medallion buyers, amid competition from Uber and Lyft. In a complaint filed on Wednesday in Manhattan federal court, the SEC said Medallion and President Andrew Murstein paid a California media strategist to anonymously promote Medallion on websites including Huffington Post, Seeking Alpha, TheStreet.com, and Crain’s New York Business. Murstein, 57, a Medallion founder whose family is the New York-based company’s largest shareholder, allegedly kept touters on Medallion’s payroll for nearly two years and paid hush money to keep one quiet. According to the complaint, Murstein also fraudulently inflated the value of Medallion’s banking unit to offset loan losses, and against his auditor’s advice fired a valuation firm that refused to vet the scheme. The alleged schemes occurred from 2014 to 2017, as the …