500Friends Inc., developer of a social loyalty and rewards platform for retailers, said Wednesday that it had raised $4.5 million in Series A financing. According to a regulatory filing, the financing reached $5.9 million and included preferred stock issued from converted promissory notes. The company has raised money from a slew of investors, including Y Combinator; Quest Venture Partners; ZenShin Capital; StubHub.com founder Jeff Fluhr; other and individual investors including Steve Newcomb, Eric Chen and Naval Ravikant. According to the company’s website, customers include Hotels.com and PetFoodDirect. 500Friends is based in San Francisco.