China just moved a step closer to acquiring one of America's oldest stock exchanges, despite security concerns raised by some in Congress.

This week a U.S. panel that examines foreign deals for potential national security concerns cleared the purchase of the 134-year-old Chicago Stock Exchange by a China-led group of investors.

The Chicago Stock Exchange said the Committee on Foreign Investment in the United States (CFIUS) decided there are "no unresolved national security concerns" over the deal, which was first announced in February.

A U.S. Treasury spokesperson declined to comment, citing policy not to disclose information about specific CFIUS cases.

Representatives for CFIUS did not respond to a request for comment on the news, which was first reported by Reuters.

The acquisition by China's Chongqing Casin Enterprise Group still faces SEC approval. If cleared, the deal would give China a foothold in the vast American stock market, the largest in the world.

The struggling Chicago Stock Exchange is far smaller than the Nasdaq (NDAQ) and the iconic New York Stock Exchange. Earlier this year it accounted for just 0.5% of U.S. trading.

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Still, some lawmakers raised security concerns about Chinese investors buying into the U.S. equity market.

Dozens of members of Congress wrote a letter in February urging the deal receive tough scrutiny and get blocked if the buyer had close ties to the Chinese government.

The Chicago Stock Exchange transaction was proposed during a different atmosphere.

Since then, President-elect Donald Trump and China have clashed over the U.S. position that Taiwan is part of "one China." Beijing has said it is "seriously concerned" by Trump questioning this long-standing policy. Trump has also accused China of devaluing its currency, even though Beijing is spending heavily to keep the yuan from falling too quickly.

Trump was very critical of China's trade tactics during the presidential campaign, threatening to slap a 45% tax on Chinese goods coming into the U.S.

If the Chicago Stock Exchange deal is cleared, it won't be the first instance of foreign ties to a U.S. exchange. In 2007, Nasdaq merged with OMX, a Nordic exchange, becoming Nasdaq OMX Group. The exchange has since changed its name back to Nasdaq.

The Chicago Stock Exchange is minority controlled by a group that includes Bank of America (BAC), E*Trade (ETFC), Goldman Sachs (GS) and JPMorgan Chase (JPM).