Apollo Residential Mortgage Inc.’s initial public offering of at least 10 million shares priced at $20 each Thursday, as expected. The offering’s size and price matches the company’s estimated terms, released last week. It had originally registered for an offering worth up to $300 million in March. Apollo is a newly formed real-estate finance company meant to focus primarily on mortgage-backed securities, residential mortgage loans and other residential mortgage assets in the U.S. It is planning to become a real-estate investment trust.