American Capital Mortgage Investment Corp., a Bethesda-based mortgage real estate investment trust, this week reported net income for the quarter ended Dec. 31 of $16.7 million, or 33 cents per share. American Capital Mortgage posted a loss for the same period in 2013. Revenue for the quarter was $35.6 million and $154.7 million for the year. The company reported net income for the year at $156.5 million, or $3.06 per share.