The world’s second-largest stock exchange Nasdaq has revealed that seven crypto exchanges are already using its market monitoring technology, Forbes reported Jan. 30.

Just two of these seven collaborations have to date been publicized — the Winklevoss twins’ Gemini exchange, and Vctrade, run by Japanese financial services giant SBI Holdings.

The stock market giant shared its rigorous vetting system for crypto industry players that seek to use its surveillance technology, known as the SMARTS Market Surveillance system. SMARTS is a cross-market, cross-asset surveillance tool that correlates real-time and historical data with detection patterns to trace illegal market activities, such as spoofing and wash trading.

A Nasdaq representative told Forbes that the firm assesses prospective cryptocurrency clients according to three broad criteria — their business model, Know Your Customer and Anti-Money Laundering measures and exchange governance and controls.

Forbes reports that the first two criteria in particular revealed Nasdaq’s particular concern for reputability.

The last criterion reportedly includes an inquiry into how transparent a platform is in regard to their listing procedures for new crypto assets.

Around 20 Nasdaq employees are thus reportedly tasked with assessing whether the applicant crypto exchange has not only the technical capacity, but also the “moral inclination” to use the anti-market manipulation tool judiciously.

Tony Sio, from Nasdaq’s market surveillance division, told Forbes:

“Historically, we don’t do such a large vetting process for our clients because they are much more well-known. But as we started working with less well-known names, startups, then we realized we needed to do this check process.”

Last November, Nasdaq revealed a partnership with United States investment firm VanEck to jointly launch a set of regulated and surveilled digital assets products, which are set to harness the SMARTS system.

Crypto exchanges have implemented other tech from Nasdaq in the past. For example, recently launched tokenized asset trading platform, DX Exchange, uses the firm’s Financial Information Exchange (FIX) protocol.

Just this week, Nasdaq joined Citigroup and Mike Novogratz’s crypto-focused merchant bank, Galaxy Digital Holdings in a $20 million investment in a blockchain and smart contract platform for capital markets.

Earlier this month, Adena Friedman, Nasdaq’s president and CEO, said she believes crypto will have a role in the future of the global economy, characterizing “the invention itself [as] a tremendous demonstration of genius and creativity.”