As 3,200 advisors and financial professionals headed into Orlando on January 29 for TD Ameritrade Institutional's annual conference, the custodian's president Tom Nally reported that the firm now holds about $260 billion in institutional assets under management. That is double the $130 billion in assets that the firm held less than three years ago.

Nally declined to break down what percentage of asset growth came from organic growth, versus market appreciation and new advisors affiliating with the custodian. He did say that in its most recent quarter, the firm added $14.5 billion in net new assets, of which 75 percent came from the institutional side. When combined with its retail brokerage, TD now holds about $600 million in assets.

In 2012, TD experienced a record number of net new advisors and brokers affiliating with the firm. While the number of advisors and brokers moving to TD declined somewhat in 2013, the offices that did select TD were larger than in past years.

Asked about the biggest challenge that the custodian faced in the next few years, Nally cited the demographic tidal that is underway as baby boomers begin to retire and younger generations enter their peak earning years. Advisors need to bring younger colleagues and associates into their firms.

"If you don't adapt, you'll go the way of T. Rex," Nally said.