Amazon is warning investors of one of the biggest problems facing its online marketplace: counterfeit products. Under the “risk factors” section of its annual report, Amazon added a new line addressing counterfeit problems on its marketplace. “We also may be unable to prevent sellers in our stores or through other stores from selling unlawful, counterfeit, pirated, or stolen goods, selling goods in an unlawful or unethical manner, violating the proprietary rights of others, or otherwise violating our policies,” the filing said. The disclosure reflects Amazon’s increased concern over the counterfeit problem on its marketplace, as the words “counterfeit” and “pirated” were never mentioned in its annual filing before. While Amazon publicly says it has a “zero tolerance” policy for counterfeit products and has built new technology to deal with the problem, its marketplace that allows third-party merchants sell goods continues to be plagued by knockoffs. Read more at CNBC.