The 8-year-old business is backed by Spark Capital,  Founders Fund, Uncork Capital, Slow Ventures and more. : Shortly after closing a $100 million pre-IPO round, food delivery business Postmates has confidentially filed documents with the Securities and Exchange Commission for an upcoming public offering, Bloomberg first reported and the company confirmed in a blog post. The company will debut on the stock exchange at a more than $1.85 billion valuation — the valuation it garnered with its $100 million in January. In total, Postmates has raised $681 million in venture capital funding from investors including Spark Capital, Founders Fund, Uncork Capital and Slow Ventures.