U.S. Sen. Elizabeth Warren on Thursday requested a formal Securities and Exchange Commission investigation into four financial firms, asking the agency to evaluate whether they violated securities laws in an effort to thwart a federal initiative aimed at protecting investors.

At issue is the Obama administration’s proposed rule that would require financial firms to put customers' interests ahead of their own when advising them on investment decisions. The White House says the rule is necessary because, it argues, conflicts of interests in investment advice cost consumers $17 billion a year in lost earnings. In recent months, groups tied to the financial industry have mounted a campaign to stop the proposed rule, and legislation has been introduced in Congress to kill it.

In her letter to SEC Chairwoman Mary Jo White, Warren notes that as part of their pushback against the proposed rule, financial firms have filed official comment letters with the Department of Labor registering their opposition to the proposal, and asserting that it would harm their business. But the Massachusetts Democrat argues that the statements of opposition in some firms’ letters conflict with other statements in which they downplay the effect of the rule on their enterprises. She notes that securities laws generally prohibit corporate officials from making false or misleading statements about their business prospects.

“Both sets of industry claims — that the proposed rule will harm them and their business model, and that the proposed rule will not harm them and their business model — cannot possibly be true,” wrote Warren, who supports the proposed rule. “And if one of these public statements is materially false, it would appear to violate longstanding interpretations of our securities laws.”

Warren's letter spotlights four examples of what she says are discrepancies between the statements made by corporate executives during earnings calls and the letters their firms or affiliates sent to the Labor Department last July.

— The CEO of Lincoln National, Dennis Glass, told the Labor Department that the proposed rule was “so burdensome and unworkable that financial advisers and firms would not be able to use it.” However, two months earlier, when Glass was asked about the rule on an earnings call, he said his company will “be able to navigate through whatever comes down the road” and added that “we don’t see this as a significant hurdle for continuing to grow” their investment business.

— Jackson National Life Insurance Company President James Sopha told the Labor Department that the fiduciary rule would "be very difficult, if not impossible for financial professional and firms to comply" with — and that firms would be “unable or unwilling to afford the high compliance costs” that would come with it. The next month, though, the head of National Life’s parent company, Mike Wells, told investors that Jackson would benefit from the rule. He said: “My view on this DOL issue is, we will weather it well. We’ll come out on the other side, advantaged again. And Jackson has the capabilities, relationship, distribution, to build whatever product is appropriate under that set and adapt faster and more effectively than competitors.”

— A top Prudential Financial executive told the Labor Department that the proposed rule “will present a significant challenge” and increase expenses. The month before, though, another Prudential Financial official told investors that “our business mix and the strength of our franchises position us pretty well for adapting to any changes that are brought about by this regulation.” The same official said the rule would not prevent the firm from making its offerings “available on terms that work for everybody."

— A Transamerica executive told the Labor Department that the fiduciary rule proposal was “unworkable” and would have a “harmful impact.” Yet the CEO of Transamerica’s parent company soon said on an earnings call that despite the rule, the company expected to “remain very strongly positioned in a market that is providing products that millions of customers in the U.S. continue to need." He also said his company has “the track record of being able to adjust our product offering, our product design and also sales and marketing practices in order to reflect what the new regulation will be.”

In response to Warren’s call for an SEC investigation, spokespeople for two of the companies, Transamerica and Prudential, suggested there were no discrepancies in their companies’ public statements.

“As we have said consistently, the Department of Labor fiduciary rule could have the unintended consequence of limiting client access to financial advice and retirement solutions,” Prudential spokesman Scot Hoffman said. “We have a business mix and business strategies that enable us to navigate that potential disruption better than most of our competitors, but that does not lessen our concerns.”

Legal experts, however, told International Business Times that the statements from the companies appeared to be in conflict, raising questions about whether they violate federal securities laws that bar corporate officials from making public statements that might deceive investors.

“Securities laws are put there to hold people’s feet to the fire to make sure that public statements they are making are not inconsistent. But when they open their mouths, people have to tell investors the truth, the whole truth and nothing but the truth,” said University of Tennessee law professor Joan Heminway. “For political reasons these companies are making statements because they don’t want additional regulation; but on the other hand, they also want to assure investors that nothing material or significant is going to impact their businesses. In doing so they create an environment in which investors could be misled.”

Ann Lipton, a Tulane University Law professor, noted that regulatory matters in particular have been an issue when it comes to legal questions about false statements.

"Companies have gotten into trouble in the past by falsely saying that regulatory proposals weren’t going to have an effect, and if that’s what’s going on here, the company could be opening itself up to serious liability," Lipton told IBT.

But University of Idaho law professor Wendy Couture pointed out that whether the discrepancies rise to the level of prosecution is based, in part, on whether the statements changed investor behavior.

“Not all false statements are actionable as securities fraud,” she said. “That depends on whether there is a significant likelihood that a reasonable investor would consider the information to be significant in making an investment decision.”

At least one watchdog group says that the statements warrant a probe.

“It is standard practice in the finance industry to say one thing in the fact-free zone of Washington, D.C., and a totally different and often contradictory thing to shareholders,” said Dennis Kelleher, who runs the group Better Markets, which is pushing the fiduciary rule. But, he added, “Senator Warren has identified sufficiently contradictory public statements that a reasonable investor might rely on for the purchase or sale of a security and, therefore, the SEC should commence an investigation.”