NEW YORK ( TheStreet) -- Insider trading may be a new risk to international dealmakers seeking to buy U.S. companies, as regulators begin a review of what could be the largest-ever acquisition by a Chinese buyer of a U.S. firm. In a Thursday complaint, the Securities and Exchange Commission brought forward allegations a Thai trader may have illegally profited from inside information about the recently announced proposed purchase of Smithfield Foods ( SFD) by Shuanghui International Holdings. The allegations come after a string of similar complaints involving acquisition efforts by emerging market firms for North America companies, and raise the prospect that insider trading concerns could put a damper on international mergers. In the wake of Smithfield's announced acquisition by Shuanghui for $4.7 billion, most media reports are focusing on how the deal among pork industry heavyweights will test regulators' resolve to allow Chinese firms to invest in the United States. Senators, regulators and the Committee on Foreign Investment in the United States (CFIUS) will take a close look at whether Smithfield's acquisition raises national security concerns. A bigger issue, however, may be the rash of insider trading allegations after the SEC said Thursday it froze the assets of a Thai trader who the regulator alleges made an illicit profit of $3 million on a tip about Smithfield's sale to Shuanghui. Other large cross-border deals, notably Heinz's ( HNZ) pending acquisition by Berkshire Hathaway ( BRK.A) and 3G Capital of Brazil and CNOOC's ( CEO) acquisition of Canadian oil and gas driller Nexen ( NXY) have also been bogged down by insider trading inquires. Allegations of impropriety tied to such high profile deals could cool U.S. firms' interest in selling to foreign buyers, given less strict regulation in emerging markets such as China and Brazil. The allegations may also give U.S. regulators new reasons to be skeptical of foreign acquisitions of U.S. firms, beyond traditional CFIUS reviews. To be clear, none of the companies involved in large recent deals are accused of any wrongdoing. Instead the SEC allegations or inquiries target brokers, bankers and traders who may have benefitted from non-public inside information in trades prior to the announcement of each deal. In Thursday's allegations, the SEC claims Badin Rungruangnavarat of Thailand purchased thousands of out-of-the-money Smithfield Foods call options and single-stock futures contracts from May 21 to May 28 in an Interactive Brokers account after receiving material, nonpublic information about the firm's potential acquisition. The SEC's complaint states that one of Rungruangnavarat's sources of non-public material information was a Facebook friend who is an associate director at an investment bank a company that was exploring an acquisition of Smithfield.