Investors that know the mortgage-bond business know Michael A. J. Farrell. Farrell was a founder of FIDAC, the advisory company behind Annaly Capital (NYSE:NLY), as well as Chimera Investment (NYSE:CIM) and CreXus Investment (NYSE:CXS.DL).

A longtime bond trader who came up through Merrill Lynch, Morgan Stanley (NYSE:MS), and L.F. Rothschild Mortgage, Farrell's views on the mortgage-bond market were closely watched by those heavily involved in the industry. Aside from opining during Annaly's quarterly conference calls, Farrell also offered up a quarterly "insight" (past installments available here) with his views on where the market was headed. 

Back in January, Farrell was diagnosed with cancer, though it was believed that it had been caught early and would be treatable. Annaly appointed Farrell's longtime associate, Wellington Denahan-Norris, to co-CEO earlier this month to allow Farrell to focus on his treatment. In a statement on Sunday, Annaly issued a press release from its board:

It is with profound sadness that we today announce the passing of Michael A.J. Farrell, co-founder, Chairman and Co-CEO of Annaly Capital Management. He was a fantastic leader and friend and will be greatly missed. Our hearts go out to his family and all those who were fortunate enough to know him.

Under Farrell's leadership, Annaly returned more than 600% for its investors since the company's initial public offering, and it, along with fellow mortgage REITs, has become a hot topic for investors as the quest for yield has drawn attention to the sector's double-digit yields.

Though not as well known as Farrell, Denahan-Norris was a co-founder of FIDAC with Farrell and has been the chief investment officer of FIDAC for the past decade and a half. Denahan-Norris also worked with Farrell prior to the founding of FIDAC. 

We here at The Motley Fool are sorry for the passing of Michael Farrell and extend our deepest condolences to his friends and family.

Matt Koppenheffer owns shares of Morgan Stanley. The Motley Fool owns shares of Annaly Capital Management. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.