A new report drafted by the New York attorney general’s office (OAG) alleges that a significant number of cryptocurrency exchanges may be vulnerable to market manipulation, a finding that could prove ominous for hopes among investors that federal regulators will approve a bitcoin ETF or other exchange-traded crypto products in the near-term.

Bitcoin, according to Securities and Exchange Commission (SEC) Chairman Jay Clayton, is not a security under federal law. However, an exchange-listed fund that provides investors with exposure to bitcoin would be a security, which is why the approval of these products falls under the SEC’s purview.

While several bitcoin ETF applicants have sought to create a fund whose shares would be backed by physical BTC, the sentiment among most analysts is that the first cryptocurrency ETF to receive a green light from the SEC will be one that holds bitcoin futures, which are already regulated by the Commodity Futures Trading Commission (CFTC).

Currently, bitcoin futures are available on two regulated U.S. stock exchanges — CME and CBOE, both of which are based in Chicago. CBOE was the first to market with its cryptocurrency product, though CME’s sees much more average daily trading volume and bases its pricing data on a wider array of spot trading markets.

This is where the OAG report comes in. The report, published on Monday, is the culmination of a five-month investigation into the operations of 13 cryptocurrency exchanges. Among other things, the OAG examined whether exchanges, in its view, adequately combat market manipulation.

As noted by Bloomberg’s Matt Leising, three of the cryptocurrency exchanges that provide pricing data for CME’s future contracts had policies that the OAG flagged as problematic.

One, Kraken, incurred the OAG’s ire for publicly flouting the state’s inquiry, with CEO Jesse Powell arguing that market manipulation “doesn’t matter to crypto traders.” The report said that two others, Bitstamp and itBit, have no formal policies in place to prevent market manipulation.