A suspicious stock spike might boost legislation that seeks to bring a clandestine class of Wall Street representatives into the daylight.

At least that’s what proponents such as Sen. Charles E. Grassley, R-Iowa, and Rep. Louise M. Slaughter, D-N.Y., are banking on.

The unlikely duo of lawmakers share a passion for shining a light on the shadowy world of political-intelligence operatives. They’ve tried for years and almost found success with an amendment to the STOCK Act, but now they and their allies see a new opportunity amid investigations into a piece of advance information that sent health care stocks soaring.

“We need transparency of who these people are, what the industry does, just like we do lobbying,” Grassley told me last week. “Transparency brings accountability.”

Political-intelligence operatives scour Capitol Hill and work their contacts in the executive branch for the latest information about upcoming legislation or federal agency decisions. Then they quickly ferry that intel back to Wall Street traders.

They’re under no obligation to report their clients or fees.

“It’s difficult to trace,” Grassley noted. “Obscure people are talking to people they know, or maybe people they don’t know, and they ask questions that may appear innocent to the guy being questioned, but then it ends up being valuable economic espionage information.”

Sometimes regular lobbyists play in the political-intelligence world, and though they may disclose their advocacy clients, their information-only clients are off the books to public eyes. Other times, former government aides or industry analysts have made specialties purely out of political-intelligence gathering.

In an odd twist, the recent health care stock spike appears to involve a former Grassley aide who now works at the law and lobbying firm Greenberg Traurig (made famous for its former employee: convicted lobbyist Jack Abramoff).

The Wall Street Journal first reported that Greenberg Traurig’s Mark Hayes is involved in a widening probe about whether he may have passed on nonpublic information to an investment firm about a Medicare rate decision. The outfit, Height Securities, sent out an alert to traders, which sent the stocks of certain health care firms on a spike.

Now, Grassley has launched an investigation, and the Securities and Exchange Commission and Health and Human Services also are looking into the matter.

Slaughter said traders made more than $600 million in 18 minutes off the tip. If her cause had been looking for a “classic case about what political intelligence does,” she says she’s found it.

“We do not exist to affect the markets,” Slaughter said last week, her voice rising. “As a member of Congress, I am grievously offended by this.”

Slaughter said her proposal would exclude reporters, who trade in not-yet-public information (but for a typically far lesser price than stock traders).

Craig Holman, a lobbyist with Public Citizen who is working with Grassley’s and Slaughter’s offices on the bill, said roping political-intelligence operatives under the Lobbying Disclosure Act is the right path. They would likely have their own category separate from lobbyists, and it might include their own stock trades.

“What we’re trying to capture is the real insider game,” Holman said.

Of course, as any K Street insider knows, the LDA itself has plenty of loopholes — advocates who spend less than 20 percent of their time on lobbying activities, for example, are exempt. I call them “unlobbyists.”

American League of Lobbyists President Monte Ward said he sees no problem in bringing covert Wall Street operators into the LDA. While lawmakers are at it, he suggests, they could also tighten the loopholes to bring more unlobbyists out of the shadows.

“If you’re involved in the political process, we want everything to be as open and transparent as possible,” Ward said. “We want to make sure everybody who is involved is captured … to make sure we don’t have anybody crossing the line.”

Just how this will work won’t be easy, though.

“Defining what political intelligence is and what meets the definition is going to be a chore,” said Ken Gross, a partner at Skadden, Arps, Slate, Meagher & Flom who specializes in ethics and lobbying compliance.

But, he said, if there is a disclosure scheme, “it’s going to raise the ante. It will spread the bread crumbs for the regulator to look more carefully at the activity.”

You wouldn’t get an argument from Grassley there.

“Knowledge is power,” the senator said. “And in the case of political intelligence, knowledge is dollars.”

Kate Ackley is a staff writer at CQ Roll Call who keep tabs on the influence industry.