While hard at work in Washington, a handful of members of Congress have also been busy trading stocks.

An analysis published on Sunday by Politico found that 28 members of the House of Representatives and six senators who served in the 114th Congress each traded more than 100 stocks in the past two years. And while the trades aren't necessarily illegal, they do raise questions -- especially considering some lawmakers are buying and selling stocks that could be affected by their work on Capitol Hill.

Health and Human Services Secretary Tom Price has been subject to scrutiny over his trades as a Representative from Georgia. Democrats have decried his investing activity after a Wall Street Journal report revealed he traded more than $300,000 in shares of health-rated companies over a four-year period while sponsoring and advocating legislation that would affect those companies' stocks.

His investment in a small Australian biotech company, Innate Immunotherapeutics, in particular sounded the alarm bells in light of the fact that Representative Christopher Collins of New York, another Trump ally, had made similarly conspicuously-timed trades. Perhaps even more troubling: Politico's research found as the scandal brewed around Price and Innate Immunotherapeutics, more members of Congress bought shares of the company.

Of course, Price isn't the only member of Congress to have done some stock investing. Politico found that three in 10 congressmen and women have made a stock trade over the past two years, totally 21,300 trades in total.

Stock trading is relatively even between the two parties -- 31% of Republicans made a trade, as did 28% of Democrats. Thirty-nine percent of senators traded, compared to 28% in the House, but, 11 of the top 12 traders are House members.

Representative Mike McCaul (R-TX) is among the most prolific traders on Capitol Hill. He reported about 7,300 transactions over two years.

To be sure, trading stocks by members of Congress is not exactly illegal. The STOCK Act, signed by President Obama in 2012, prohibits insider trading, but it doesn't bar investing altogether.

"There are always some gray areas," Larry Noble, general counsel of Washington, D.C.-based watchdog the Campaign Legal Center, told the Washington Post in January.

Interested in seeing what members of Congress have been buying and selling? Click through to see what Politico's research revealed.