WASHINGTON -- Sen. Richard Burr's vocal opposition to the STOCK Act raised some eyebrows in Washington this week, and with good reason.

Burr, a North Carolina Republican who was one of just three senators to vote against the ban on congressional insider trading Thursday, owns investments in the natural gas industry that would benefit from legislation he co-sponsored offering tax credits for natural gas-fueled vehicles.

Burr has investments in the gas industry valued from $133,298 to $219,337, according to his 2010 filings. His portfolio includes $36,000 worth of stock in Chesapeake Energy Corp., the second-largest U.S. producer of natural gas. He also holds more than $25,000 in shares of Loews Corp., a holding company with subsidiaries engaged in the exploration, production, marketing and transmission of natural gas.

He was on the losing side of Thursday's 96-3 passage of the STOCK Act, that would tighten rules for lawmakers and their aides using inside information for personal investments. House Majority Leader Eric Cantor said he'll bring the STOCK Act to the House floor next week.

Burr's investments pose "a very clear conflict of interest," said Craig Holman of the advocacy group Public Citizen. He said the STOCK Act "will make members of Congress much more cautious in any particular sector, including natural gas." While the STOCK Act wouldn't prohibit such investments, "members of Congress will have to think twice about any kind of trading activity they do," Holman said.

Burr was unavailable to discuss his investments, his office said. He opposed the STOCK Act "because there are already laws in place to address this critical issue," said spokesman David Ward. "Laws regarding insider trading that apply to the American people also apply to members of Congress and their staff. Members of Congress are elected to serve the people, not make money for themselves, and any member or staff member who breaks the already existing insider trading laws should be held responsible."

Burr, along with Georgia Republican Sen. Saxby Chambliss, and two other senators introduced S-1863 in November with bipartisan support. The measure would offer individuals and businesses tax credits for buying natural gas-fueled vehicles or converting existing fleets to run on the fuel. President Barack Obama on Friday said he supported the bill.

Chambliss has $15,000 in the BlackRock Growth Fund, according to the most recent documents available. The fund, with an estimated $1.9 billion in assets, bet heavily on coal and natural gas in 2011, targeting what it saw as an expected rise of the price of energy in both sectors.

Chambliss' office declined to comment.

Despite his STOCK Act opposition, Burr has said he supports the ban on congressional insider trading. In a recent interview with Jerri Jameson on News Radio 570- WWNC, Burr called the STOCK Act "ludicrous" and "political theater."

"We should be focused on jobs, the economy," he said. "We should be taking up real legislation. It’s like me saying to you, 'Jerri, before you come to work this morning and you’re going to drive your car, I’m going to pass a law that says you have to have a driver’s license' ... The laws that are currently on the books apply to all members of Congress and all staff, not limited staff."

