Postmates CEO Bastian Lehmann on 'choppy' public markets, competitors and more. : In a wide-ranging conversation at TechCrunch Disrupt San Francisco last week, Postmates co-founder and chief executive officer Bastian Lehmann made light of the company’s lack of IPO documents. The San Francisco-based on-demand delivery business was expected to publicly file its IPO prospectus in September in preparation for a fall exit, sources familiar with the matter told TechCrunch this summer. September, however, has come and gone and we’re still waiting on Postmates to release the critical document.