By Patrick Rucker and Sarah N. Lynch

WASHINGTON (Reuters) - The U.S. Securities and Exchange Commission raised questions about Wells Fargo & Co's <WFC.N> aggressive cross-selling in late 2014, according to regulatory paperwork, almost two years before officials settled with the bank for opening phony accounts.

In December 2014, the SEC asked Wells Fargo to detail how it tallied the many accounts that one customer might open.

"Your cross-sell program is a key element that management believes will help Wells Fargo meet its strategic goals," reads the letter from Christian Windsor, an SEC attorney in the Division of Corporation Finance.

"Please provide us with an explanation of the methodology you use to calculate the products per household."

The same letter asks Wells Fargo to explain how it measured cross-selling success in the past.

Wells Fargo's Controller Richard Levy responded to the regulator on Jan. 12, 2015, saying that its methods to measure cross-selling "remained consistent" over the past five years.

The bank wanted savings accounts, individual retirement accounts or other products that "have the potential for revenue generation and long-term viability," the bank wrote.

Last month, federal banking regulators ordered Wells Fargo to pay $190 million to settle civil charges that it had opened personal accounts without customer say-so to satisfy managers' demand for new business.

The SEC letter makes no mention of how unauthorized accounts might affect cross-selling metrics.

By early 2015, Wells Fargo had fired several thousand employees for the opening of unauthorized accounts.

Federal prosecutors and other U.S. agencies are now probing the bank, sources have said.

It is unclear exactly what prompted the SEC's Corporation Finance Division, which reviews company filings, to ask questions about cross-selling and whether the SEC was satisfied with the response.

An SEC spokesman declined to comment.

Last month, several U.S. Senate Democrats called on the SEC to investigate whether Wells Fargo misled investors by failing to disclose what they called "widespread fraud."

In a separate letter in October 2007, the SEC asked Wells Fargo about its formula for compensating executives. The bank said cross-selling success could mean higher pay.

"Wells Fargo has designed its management reporting system and goal-setting process to facilitate and reward these behaviors," the bank wrote the SEC in October 2007.

John Stumpf, Wells Fargo's chief executive officer, was copied on both letters. On Wednesday, Stumpf stepped down from the bank.

(Reporting By Patrick Rucker; Editing by Bernard Orr)