 Bloomberg -- Attorneys general from New York and California are partnering with the Federal Trade Commission to investigate Amazon.com Inc.s online marketplace, according to people familiar with the matter, ratcheting up scrutiny of the worlds largest e-commerce company.The three agencies will work together to interview witnesses in coming weeks on joint conference calls, the people said. Bloomberg reported on the FTC investigation last year, and Californias probe was revealed in a court filing last week. The New York investigation and collaboration among agencies at the state and federal level hasnt previously been reported.State and federal regulators cooperating can often precede a big antitrust enforcement action, similar to that taken against Microsoft Corp, said Diana Moss, president of the American Antitrust Institute.This appears to be taking the shape of what could be a major collaborative antitrust investigation, she said. This happens in big cases where the feds have a stake in enforcing the law, and also when states have an interest in protecting their constituents.Through spokespeople, Amazon, the FTC and the offices of Californias and New Yorks AGs all declined to comment.New York Attorney General Letitia James is also investigating the termination of Chris Smalls, who led a demonstration at an Amazon warehouse in Staten Island. Amazon has said Smalls and three other activist workers were fired for violating company policy.Amazon is among four big technology companies being scrutinized for allegedly abusing their market power. Along with the chief executives of Alphabet Inc., Facebook Inc. and Apple Inc., Amazons Jeff Bezos testified last week before a House committee probing antitrust allegations.Almost 40 cents of every dollar spent online in the U.S. goes to Amazon, which has more of the online retail market than its nine closest competitors including Walmart Inc. and EBay Inc. combined, according to EMarketer Inc. Amazon, which denies abusing its market position, has said it represents a small fraction of total U.S. retail sales.Updates with background starting in sixth paragraph.For more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.2020 Bloomberg L.P. 