Three years after the last recession began, gathering retail deposits is a game where every bank's a winner. Even the ones that don't want to be.

Data gathered by the deposit research firm Market Rates Insight shows that total deposits increased by a full trillion dollars in the 36 months preceding October, despite the steady plunge of rates paid in that same time frame. Historically considered to be elastic in supply, the quantity of deposits now entering the banking system appears to be insensitive to interest rates that banks offer.

A consequence of retail banking customers' demand for safety above all else, the trend is complicating banks' efforts to match their assets with funding — and raising questions about how low even non-inflation-adjusted rates can go. If customers come to view deposit accounts as a simple insurance product, suggested Dan Geller, Market Rates Insight executive vice president, they might even pay to put their money there.

Though few institutions would publicly discourage new customers from bringing in money, indications abound that many institutions have had their fill. The average annual percentage yield offered at the institutions Market Rates Insight monitors have been dropping at a steady clip, down to 0.8%. The average yield on nine-month certificates of deposit is now lower than that offered by a fully liquid money market account. And, Geller said, a growing number have introduced savings accounts with a 1 basis point annual percentage yield.

"It's a polite way of saying, 'please, we really don't want the money,' " he said.

But while some of Geller's deposit-saturated clients have deliberately set uncompetitive rates, that hasn't shut off the spigot. "The impact of lowering rates is negligible," he said.

The shift has upended traditional competitive advantages in the industry, said Paul Miller, managing director of FBR Capital Markets. "It used to be deposit gathering was the value add, and lending was the commodity. That may have switched now," he said. "Every quarter, more and more banks come to the realization, 'why are we collecting deposits to buy securities?' It's a capital hit."

Yet some banks are seeking to maintain their deposit appetite. Fiaz Sindhu, an executive in Accenture's North American banking practice, argued that banks should invest in pricing analytics to keep their rates in line with declining yields, but still competitive.

Given low-rate deposits' propensity to stick around even after rates rise, Sindhu said, he advises clients to lard up on them in anticipation of an eventual recovery.

Sindhu said that it also was important for banks to remember that deposit gathering is traditionally a source of new contacts with customers who may provide more valuable business on brokerage or other fronts.

But he, too, dismissed the idea that anyone could, or would want to, compete heavily on rates in the current environment. Instead, Sindhu suggested that banks would be better off focusing on offering deposit products with market-linked rates or other promotions. Once in the door, many of those customers would likely stay with the bank, he said.

"The spreads are so small between the institutions, right now it's about the [consumers'] switching costs, not the spread," he said. "I don't think everyone's a rate hunter. The value of the stickiness shouldn't be understated."

A similar philosophy led Wells Fargo & Co. Chief Executive John Stumpf to extol the company's deposit-gathering efforts at an investor conference this week.

"While you could argue that your free deposits aren't so valuable because where are you going to invest them today, I think that's a very myopic and short-term way of looking at it," Stumpf said. Wells is happy to bring in the money in the hope that it can sell a person "six products, seven, eight" if they open up a new account.

While Wells may still value its deposits, however, that doesn't necessarily mean it is willing to pay for them. In its home state of California, the company's posted current rate on savings accounts tops out at 0.35% — and that's for a bundled product with a $25,000 minimum deposit.

As loans reprice downward in the current environment, Geller said, he expects that more institutions will both continue to lower their average percentage yields and seek to adjust their funding to what he calls "just-in-time inventory."

"If the demand for lending is x, you raise y amount of deposits to satisfy the regulations," he said. "But not over that."