There are the big mortgage servicing deals, and then there are the quieter, steadier streams of new MSR business Nationstar Mortgage Services (NMS) is collecting every month.

The Texas-based mortgage servicer announced another big $10.4 billion acquisition of servicing rights from Bank of America (BAC) Tuesday. Nationstar CEO Jay Bray spoke at a conference put on by investment bank Keefe, Bruyette, and Woods shortly after the announcement.

With the purchase of some Aurora Bank servicing earlier in the year, Nationstar grew its portfolio to $166 billion from $103 billion, Bray said. The firm will swell to the largest nonbank servicer in the country if the Residential Capital deal goes through in December.

But Nationstar will board more loans from large banks monthly to go with other bulk deals it's still pursuing, Bray said.

"From a servicing standpoint, there's a paradigm shift to flow servicing," Bray said. "Not only are you seeing opportunities to acquire large pieces of servicing, but there's now a trend of financial institutions wanting to flow servicing into organizations like ourselves. We have a few relationships with some companies."

One such company may be BofA itself. While a spokesman for the bank could not comment on specific MSR transactions, he did say BofA periodically sells servicing rights or transfers servicing to third-party providers.

"This activity is consistent with steps that Bank of America is taking to address legacy mortgage issues and better position the enterprise for growth," the spokesman said.

In just the past 12 months, BofA trimmed its servicing portfolio for investors by nearly 19% to $1.3 billion as of March 31, according to its financial filing.

Bray said the agreements mean loans will move to Nationstar once it hits a certain delinquency status, some times at 45 days past due.

He said as Nationstar looks to board more loans, it looks at the probability of keeping the mortgage current or solving the delinquency as the key driver of profitability. That's been hurt by a still struggling employment picture in the country, he said.

But, there is a lot of supply and not a lot of capable companies in the market for servicing, especially with such volatile regulatory crackdowns on abuses in the past. This, he said, allows Nationstar to buy these rights cheaply resulting in unlevered returns for the company of sometimes 20%.

Roughly $350 billion in servicing transferred from banks to nonbanks in the past two years, according to Bray's presentation. And he said there is a pipeline of an additional $700 billion that will take four to five years to move either through large deals or these monthly flows across the space.

"We view that as the gift that keeps on giving," Bray said. "We'll maintain the servicing portfolio through that process."