Two U.S. senators — Democrat John Hickenlooper of Colorado and Republican Mike Rounds of South Dakota — violated a federal transparency law by failing to properly disclose personal and family stock trades, including a pair involving a prominent defense contractor, according to a NOTUS review of congressional financial documents.

They’re the latest in a litany of lawmakers tripped up in recent months by the Stop Trading on Congressional Knowledge, or STOCK, Act, which Congress passed in 2012 to increase public transparency, curb conflicts of interest and defend against insider trading. The law, in part, requires members of Congress to disclose individual stock, bond, cryptocurrency and several other kinds of financial trades no more than 45 days after the trade is made.

Hickenlooper was nearly a year past a federal deadline when, on May 5, he reported full details of a Liberty Broadband Corporation stock sale by his wife. The value: between $500,000 and $1 million.

The senator was similarly late in disclosing the sale of stock held by his dependent child in Palantir Technologies, a defense technology company that’s scored massive government contracts with the Department of Defense and Immigration and Customs Enforcement.

While Hickenlooper valued the sale at between $2,000 and $30,000 in a filing with Congress, the senator’s office told NOTUS that the actual sale was worth $3,312. Members of Congress are only required by law to disclose the values of their stock trades in broad ranges.

Hickenlooper’s office said in a statement to NOTUS that the senator does not personally trade stocks and that his investments are held in what it described as a “blind trust.” To date, Hickenlooper’s trust has not been certified as a “qualified blind trust” by the Senate Select Committee on Ethics, a verification the committee considers a superior way of lawmakers avoiding financial conflicts of interest.

“As soon as the transactions involving the Senator’s family members were identified, the appropriate steps were taken with the Senate Ethics Committee,” Hickenlooper’s office said.

For Rounds, he was more than five months late reporting the sale of between $1 million and $5 million worth of nonpublic stock in Aeronics Inc., an equipment manufacturing company, according to a disclosure he filed on May 6.

“The sale in question was publicly disclosed when the information was made available to him,” spokesperson Arden Koenecke told NOTUS. “This non-public stock sale happened via a third-party investment firm. Senator Rounds does not have direct involvement regarding the firm’s decisions.”

Rounds “has been working hand-in-hand with the Ethics Committee” regarding the late disclosure, Koenecke added.

The offices of Rounds and Hickenlooper did not answer questions about whether the senators have paid a late-filing fine, which is $200 for first-time offenders.

The Senate Ethics Committee, which polices the STOCK Act within the Senate, declined to comment Thursday.

But the committee’s latest guidance to senators is that when it comes to complying with the STOCK Act, the buck stops with lawmakers themselves.

“It is the filer’s responsibility to monitor accounts owned by you, your spouse, and your dependent children, recognize reportable transactions, and file [periodic transaction reports] in a timely manner,” the committee states in its official financial-disclosure instructions to senators. “While you may have a discretionary account allowing a financial advisor to buy, sell, and exchange investments on your behalf, the Committee strongly recommends that you receive and review account statements on at least a monthly basis.”

Since July, more than two-dozen federal lawmakers have reportedly violated the STOCK Act, including then-Sen. Markwayne Mullin of Oklahoma and Sens. Katie Britt of Alabama and Susan Collins of Maine.

In the House, STOCK Act violators include Reps. Linda Sánchez of California, Julia Letlow of Louisiana, Jim Jordan of Ohio, Lisa McClain of Michigan, Pat Ryan of New York, Sheri Biggs of South Carolina, Donald Norcross of New Jersey, Rich McCormick of Georgia, Ritchie Torres of New York, Troy Nehls of Texas, Dan Meuser of Pennsylvania, Jonathan Jackson of Illinois, George Whitesides of California, Val Hoyle of Oregon, Austin Scott of Georgia, Shri Thanedar of Michigan, Debbie Wasserman Schultz of Florida, Pramila Jayapal of Washington state, Kelly Morrison of Minnesota, Ed Case of Hawaii and Scott Franklin of Florida. Rep. Kevin Hern of Oklahoma was also late, although his office denies it.

Other members — such as Reps. Cleo Fields of Louisiana, Dave Taylor of Ohio, Tim Moore of North Carolina and Byron Donalds of Florida — have reported making personal financial trades with notably political timing.

Amid the repeat violations, some members of Congress are pushing to ban stock trading outright for themselves and their peers.

Lawmakers in both parties have teamed up to introduce bills to end the practice. However, Republicans have been moving their own bill through the House this year to ban stock trading, a measure known as the Stop Insider Trading Act that Democrats have criticized as being full of loopholes. That partisan divide, along with the now-ended government shutdown and a war with Iran preoccupying members, has the movement losing steam — at least for the moment.

Hickenlooper’s office noted that the senator is a co-sponsor of the Ban Congressional Stock Trading Act, a Democrat-backed bill that has languished in the Senate Homeland Security and Governmental Affairs Committee since its introduction nearly a year ago. That bill requires members of Congress to use qualified blind trusts for stock holdings.

A few members of Congress aren’t waiting around and have voluntarily abstained from trading individual stocks, including Republican Reps. Rob Bresnahan of Pennsylvania and Jefferson Shreve of Indiana and Democratic Rep. Julie Johnson of Texas.