Note 2 - Organization and Nature of Business Operations	3 Months Ended
Mar. 31, 2013
Nature of Operations [Text Block]	Note 2 – Organization and Nature of Business Operations References to “we,” “us,” “our,” "JAVELIN" or the “Company” are to JAVELIN Mortgage Investment Corp. References to "ARRM" are to ARMOUR Residential Management LLC, a Delaware limited liability company. We are an externally managed Maryland corporation formed on June 18, 2012 and managed by ARRM. On June 21, 2012, an initial capital contribution of $1,000 was made to us and we issued 50 shares of common stock. On September 24, 2012, we filed Articles of Amendment and Restatement ("Articles") with the Maryland State Department of Assessments and Taxation, which increased our authorized shares of common stock, par value $0.001 per share, from 1,000 shares to 250,000,000 shares and authorized 25,000,000 shares of preferred stock, par value $0.001 per share, for issuance. The registration statement for our initial public offering (“IPO”) was declared effective on October 2, 2012. On October 3, 2012, our common stock commenced trading on the New York Stock Exchange (“NYSE”) under the symbol “JMI”. We commenced operations upon consummation of our IPO and concurrent private placement (the “Private Placement”) of our common stock on October 9, 2012. Pursuant to our IPO and Private Placement, we sold to the public 7,250,000 shares of common stock and sold 250,000 shares of common stock to Staton Bell Blank Check LLC (“SBBC”), an entity jointly owned by two of our directors, at a price of $20.00 per share. Net proceeds from the IPO and Private Placement totaled $150.0 million. On November 2, 2012, the underwriters in the IPO decided not to exercise their over-allotment option to purchase up to an additional 1,087,500 shares of common stock. We invest primarily in fixed rate and hybrid adjustable rate mortgage backed securities (“MBS”). Some of these securities are issued or guaranteed by a U.S. Government-sponsored entity (“GSE”), such as the Federal National Mortgage Association (Fannie Mae), the Federal Home Loan Mortgage Corporation (Freddie Mac), or guaranteed by the Government National Mortgage Administration (Ginnie Mae) (collectively, “Agency Securities”). Other Securities backed by residential mortgages, for which the payment of principal and interest is not guaranteed by a GSE or government agency (collectively, “Non-Agency Securities” and together with Agency Securities MBS) may benefit from credit enhancement derived from structural elements such as subordination, overcollateralization or insurance. We also may invest in collateralized commercial mortgage backed securities ("CMBS") and other mortgage related investments, including mortgage loans, mortgage related derivatives and mortgage servicing rights. From time to time, a portion of our portfolio may be invested in unsecured notes and bonds issued by U.S. Government-chartered entities (collectively, “Agency Debt”), U.S. Treasuries and money market instruments, subject to certain income tests we must satisfy for our qualification as a real estate investment trust (“REIT”). Our charter permits us to invest in Agency Securities and Non-Agency Securities. As of March 31, 2013, Agency Securities account for 88.7% of our portfolio and Non-Agency Securities account for 11.3% of our portfolio. We intend to qualify and will elect to be taxed as a REIT under the Internal Revenue Code (“the Code”) for the year ended December 31, 2012 upon filing our federal income tax return for that year. Our qualification as a REIT depends on our ability to meet, on a continuing basis, various complex requirements under the Code relating to, among other things, the sources of our gross income, the composition and values of our assets, our distribution levels and the concentration of ownership of our capital stock. We believe that we are organized in conformity with the requirements for qualification as a REIT under the Code and our manner of operations enables us to meet the requirements for taxation as a REIT for federal income tax purposes. As a REIT, we will generally not be subject to federal income tax on the REIT taxable income that we currently distribute to our stockholders. If we fail to qualify as a REIT in any taxable year and do not qualify for certain statutory relief provisions, we will be subject to federal income tax at regular corporate rates. Even if we qualify as a REIT for federal income tax purposes, we may still be subject to some federal, state and local taxes on our income.

Note 2 - Organization and Nature of Business Operations

3 Months Ended

Mar. 31, 2013

Note 2 – Organization and Nature of Business Operations

References to “we,” “us,” “our,” "JAVELIN" or the “Company” are to JAVELIN Mortgage Investment Corp. References to "ARRM" are to ARMOUR Residential Management LLC, a Delaware limited liability company.

We are an externally managed Maryland corporation formed on June 18, 2012 and managed by ARRM. On June 21, 2012, an initial capital contribution of $1,000 was made to us and we issued 50 shares of common stock. On September 24, 2012, we filed Articles of Amendment and Restatement ("Articles") with the Maryland State Department of Assessments and Taxation, which increased our authorized shares of common stock, par value $0.001 per share, from 1,000 shares to 250,000,000 shares and authorized 25,000,000 shares of preferred stock, par value $0.001 per share, for issuance. The registration statement for our initial public offering (“IPO”) was declared effective on October 2, 2012. On October 3, 2012, our common stock commenced trading on the New York Stock Exchange (“NYSE”) under the symbol “JMI”. We commenced operations upon consummation of our IPO and concurrent private placement (the “Private Placement”) of our common stock on October 9, 2012. Pursuant to our IPO and Private Placement, we sold to the public 7,250,000 shares of common stock and sold 250,000 shares of common stock to Staton Bell Blank Check LLC (“SBBC”), an entity jointly owned by two of our directors, at a price of $20.00 per share. Net proceeds from the IPO and Private Placement totaled $150.0 million. On November 2, 2012, the underwriters in the IPO decided not to exercise their over-allotment option to purchase up to an additional 1,087,500 shares of common stock.

We invest primarily in fixed rate and hybrid adjustable rate mortgage backed securities (“MBS”). Some of these securities are issued or guaranteed by a U.S. Government-sponsored entity (“GSE”), such as the Federal National Mortgage Association (Fannie Mae), the Federal Home Loan Mortgage Corporation (Freddie Mac), or guaranteed by the Government National Mortgage Administration (Ginnie Mae) (collectively, “Agency Securities”). Other Securities backed by residential mortgages, for which the payment of principal and interest is not guaranteed by a GSE or government agency (collectively, “Non-Agency Securities” and together with Agency Securities MBS) may benefit from credit enhancement derived from structural elements such as subordination, overcollateralization or insurance. We also may invest in collateralized commercial mortgage backed securities ("CMBS") and other mortgage related investments, including mortgage loans, mortgage related derivatives and mortgage servicing rights. From time to time, a portion of our portfolio may be invested in unsecured notes and bonds issued by U.S. Government-chartered entities (collectively, “Agency Debt”), U.S. Treasuries and money market instruments, subject to certain income tests we must satisfy for our qualification as a real estate investment trust (“REIT”). Our charter permits us to invest in Agency Securities and Non-Agency Securities. As of March 31, 2013, Agency Securities account for 88.7% of our portfolio and Non-Agency Securities account for 11.3% of our portfolio.

We intend to qualify and will elect to be taxed as a REIT under the Internal Revenue Code (“the Code”) for the year ended December 31, 2012 upon filing our federal income tax return for that year. Our qualification as a REIT depends on our ability to meet, on a continuing basis, various complex requirements under the Code relating to, among other things, the sources of our gross income, the composition and values of our assets, our distribution levels and the concentration of ownership of our capital stock. We believe that we are organized in conformity with the requirements for qualification as a REIT under the Code and our manner of operations enables us to meet the requirements for taxation as a REIT for federal income tax purposes.

As a REIT, we will generally not be subject to federal income tax on the REIT taxable income that we currently distribute to our stockholders. If we fail to qualify as a REIT in any taxable year and do not qualify for certain statutory relief provisions, we will be subject to federal income tax at regular corporate rates. Even if we qualify as a REIT for federal income tax purposes, we may still be subject to some federal, state and local taxes on our income.