PureStream grew both its market share and its execution performance in 2025, while its partner Nasdaq prepared to take PureStream’s streaming protocol to Europe. And it did all this without opening its book to the market makers that increasingly populate rival dark pools.
What sets PureStream apart is the reference price. Almost every US dark pool matches institutional orders at the midpoint of the national best bid and offer (NBBO). But quotes have narrowed and fewer shares are now needed to set them. As a result, the NBBO has become a less reliable guide to where size can actually trade.
PureStream takes a different route. Instead of pegging to a quote, it matches two institutions at an agreed rate of future market volume, known as the liquidity transfer rate. It then fills them on the back of real trades as they print across the market. Suppose two orders are matched at 10%, and the market then prints 500 shares at $22.255, 1,000 at $22.26 and 200 at $22.25 – the PureStream pair trades 50, 100 and 20 shares at exactly those prices. Matched at 500%, they would trade 2,500, 5,000 and 1,000.
PureStream is the only venue that references the last sale in real time, and that is structurally why streaming outperforms
Sean Hoover
The effect is to give an algorithmic order the matching characteristics of a block with the price discovery of an algo. Every execution strategy can be expressed as a participation rate, so orders seeking different rates can still cross with one another. As PureStream references trades rather than quotes, one small print can be scaled up to move a much larger quantity without moving the price. Streaming now accounts for more than 90% of volume on the venue.
“Every other venue pegs to the NBBO, and the NBBO is deteriorating as a reference. The NBBO is where the market wants you to trade. The last sale is where the market actually traded,” says chief operating officer Sean Hoover. “PureStream is the only venue that references the last sale in real time, and that is structurally why streaming outperforms.”
That conviction has shaped commercial strategy. Several rival alternative trading systems have grown share faster by admitting the same market making participants that trade on lit exchanges, which narrows the gap between dark and lit performance. PureStream has deliberately kept them out. Its bet is that institutions will reward a venue where their counterparties are other natural investors. Brokers’ own studies suggest the bet is paying off, with PureStream’s performance edge over other venues widening during the year.
Surveillance is built to match. PureStream monitors its market continuously and evaluates match outcomes against some 200 parameters to detect gaming or information leakage.
The model is also spreading. Nasdaq is an investor in PureStream and a licensee of its technology. It already runs the protocol in Canada and is preparing to launch it in Europe, covering more than 1,200 of the most traded shares across 13 markets. PureStream has also added new order types, including a benchmark-relative peg that lets investors rest orders only at prices a set distance from the day’s value-weighted average price.
PureStream is North America’s best alternative trading venue because it offers US institutions something genuinely different from the midpoint dark pool. It crosses natural liquidity at prices the market has actually traded and protects that liquidity from opportunistic flow. And one of the world’s largest exchange groups has now adopted its model.
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