Investment bank and asset management firm Piper Jaffray Cos. is buying middle-market advisory firm Edgeview Partners LP. Financial terms were not disclosed. Edgeview Partners specializes in mergers and acquisitions. Piper Jaffray said Monday that the deal will strengthen its position in middle-market mergers and acquisitions and provide a complementary investment banking business. The transaction also gives Piper Jaffray more resources for private equity firms.