Some dealers have also traded over $1 million in product.
It is already clear that the shutting of Silk Road back in 2013 didn't stop the flow of drugs from dark web markets. Since then, dozens of sites have come and gone, others have created a fairly stable ecosystem, and the items on sale have diversified into poisons, weapons, and stolen data (all of which were banned on the original Silk Road).
After Silk Road was taken down, the total revenue from a selection of markets has averaged at nearly half a million dollars a day, according to academic research.
Nicolas Christin, an assistant research professor at Carnegie Mellon University, authored a new paper along with PhD student Kyle Soska, aiming to measure the "evolution of the online anonymous marketplace ecosystem." The research will be presented at the 24th USENIX Security Symposium on Wednesday.
The pair studied the tail-end of the original Silk Road and the explosion of other markets shortly after it was closed, through to a few months after Operation Onymous, which saw Silk Road 2 and other sites taken down by the FBI and Europol.
They found that before Operation Onymous, markets such as Silk Road 2, Agora, Evolution, Pandora, and Hydra were collectively bringing in between $300,000 and $500,000 a day on average, with the peak going up to $650,000.
"At its height, I think Silk Road 2 was probably the most successful one. In February 2014 it was clearing around $400,000 [a day]," Christin told Motherboard in a phone interview.
But the vast majority of dealers on the dark web markets don't really make decent money. "About 70 percent of all sellers never managed to sell more than $1,000 worth of products," the study reads. Meanwhile, 18 percent made between $1,000 and $10,000, and only two percent cracked the $100,000 mark.
However, some true heavyweights have likely pocketed fortunes. Thirty-five sellers were shifting over $1 million worth of product, and the top one percent of vendors made up over half of all the volume transacted, the researchers write.
Before Operation Onymous, markets such as Silk Road 2, Agora, Evolution, Pandora, and Hydra were collectively bringing in between $300,000 and $500,000 a day.
The report also offers some insight into what drugs people are buying and selling. Most of the time, cannabis and MDMA made up 25 percent of sales, while stimulants followed closely behind at 20 percent. However, whenever there was a market shutdown, scam, or theft, customers appeared to get spooked away from buying drugs that have higher penalties, and cannabis shoots up to as much as half of the total market share for a while.
The research was carried out with a web crawler that archived the feedback left on marketplaces after a purchase had been made. Previous research has looked simply at the number of listings available on the site, but this a problematic approach. "It's very easy to create fake listings," Christin explained.
Leaving feedback is a staple on marketplaces: it allows users to praise or call out a dealer for the quality of their product. Some sites also make leaving these reviews mandatory, meaning that every piece of feedback—say, each review on a gram of MDMA listed for $20—likely represents one sale at that price. Although a record of a transaction like this can also be faked, it's not as easy as creating phony listings.
"While we can not directly measure the money being transacted from buyers to sellers, or packages being shipped from vendors to customers, we do make frequent observations of product feedback left for particular item listings on the marketplaces," the authors write.
The figures found largely line up with those released by law enforcement after the arrest of high profile dealers.
As for Operation Onymous, the effect has been mixed: markets have been shut down, but aggregate figures returned to more than half of their original amounts within weeks, according to the paper.
Although the markets make up a tiny part of the overall drug trade, this study suggests they are here to stay, and will continue to generate millions of dollars of revenue over their lifetime.