Nasdaq Direct Routing: How Orders Find Liquidity

Key Takeaways

• Nasdaq order routing controls whether an order stays on the Nasdaq book or sweeps other venues.
• A routing strategy like SCAN checks the Nasdaq book first, then routes out at the NBBO or better.
• DOT directed routing sends an order straight to a named venue without checking the Nasdaq book.
• An intermarket sweep order (ISO) is non-routable and trades only on Nasdaq at the displayed price.

What Nasdaq Order Routing Is

Nasdaq order routing describes how the exchange handles an order that is marketable but not fully filled by Nasdaq's own book. Rather than rejecting the unfilled part, Nasdaq can route it to other market centers, then post any remainder back on its book.

You choose the behavior with a routing strategy, a code attached to the order. The strategy sets which venues get checked, in what order, and what happens to shares left over after the route.

The Intuition

Under Regulation NMS, an order generally cannot trade through a better-priced protected quote sitting on another exchange. So if Nasdaq does not have the best price, your marketable order has to reach the venue that does.

Routing strategies automate that reach. Different strategies make different trade-offs between speed, fees, and which venues are tapped. The choice matters because some venues charge to take liquidity and others pay rebates, so the path your order takes affects the final cost.

How It Works

A routable strategy works in phases. First it checks the Nasdaq book for any shares at a price equal to or better than the National Best Bid and Offer (NBBO). It fills what it can there. Then it routes the remainder to other venues showing the NBBO or better. Finally, any shares still unfilled post on the Nasdaq book at your limit price.

Routable order phases
  1. fill on the Nasdaq book at NBBO or better
  2. route remainder to other protected venues
  3. post any leftover on the Nasdaq book

Strategies differ in the details. SCAN fills locally, routes out, then posts, and does not route again if the book later locks or crosses. STGY is like SCAN but will route out again after posting if the book becomes locked or crossed. SKIP variants skip venues that are not Reg NMS protected. DOT is directed routing: it sends the order straight to one named venue you specify and does not check the Nasdaq book at all. Cost-saving strategies prioritize low-fee venues.

Some orders are deliberately non-routable. An intermarket sweep order (ISO) executes only on Nasdaq at the best displayed price and is never routed out. The firm sending an ISO must itself have checked other venues to satisfy Reg NMS, taking that duty off the exchange.

Worked Example

You want to buy 1,000 shares and the NBBO is 25.00 bid, 25.05 offer, but Nasdaq only shows 400 shares offered at 25.05. Another exchange shows 600 shares at 25.05.

You send a marketable buy with a SCAN strategy. SCAN first fills 400 shares on the Nasdaq book at 25.05. It then routes the remaining 600 shares to the other exchange and fills them at 25.05 there. Nothing is left, so nothing posts. You got all 1,000 shares at the NBBO without violating Reg NMS, and you did not have to manage the route yourself.

Had you instead sent a DOT order to a single venue, it would have ignored the Nasdaq book and traded only at that venue, filling fewer shares if that venue lacked the size.

Common Mistakes

1. Picking a strategy by name alone. SCAN, STGY, and SKIP behave differently when the book locks or crosses. Read what each does before relying on it.
2. Forgetting fees follow the route. Routing to a high-fee venue costs more than posting locally. The cheapest fill is not always the fastest route.
3. Misusing DOT. Directed routing skips the Nasdaq book entirely. If you wanted the best available price, DOT to one venue can miss it.
4. Sending an ISO without checking other venues. The sender of an ISO takes on the Reg NMS compliance duty. Skipping that check can violate the trade-through rule.
5. Assuming leftover shares always post. Some strategies route again instead of resting. Whether your remainder posts depends on the strategy you chose.

Frequently Asked Questions

What is Nasdaq order routing in simple terms? Nasdaq order routing is how the exchange decides whether your order trades on Nasdaq, gets sent to other exchanges for a better price, or rests on the book. You pick the behavior with a routing strategy.

How does Nasdaq order routing affect investment decisions? The strategy you choose changes which venues you reach, the fees you pay, and whether leftover shares post or chase. In the example, SCAN filled 1,000 shares across two venues at the NBBO.

What is a real-world example of Nasdaq order routing? A buy for 1,000 shares fills 400 on the Nasdaq book and routes 600 to another exchange at the same NBBO price, completing the order without trading through a better quote.

How can investors use Nasdaq order routing effectively? Match the strategy to your goal: route-and-post for full fills, directed routing for a specific venue, and consider fee-aware strategies to lower cost in liquid names.

How is Nasdaq order routing different from an intermarket sweep order? Routing sends unfilled shares to other venues automatically. An ISO is non-routable, trades only on Nasdaq at the displayed price, and shifts the Reg NMS check onto the sender.

Sources

1. Nasdaq. Routing. https://www.nasdaqtrader.com/Trader.aspx?id=routing
2. Nasdaq. North American Markets Routing Strategies Guide. https://www.nasdaqtrader.com/content/ProductsServices/Trading/StrategyG.pdf
3. Nasdaq. North American Markets Order Types and Modifiers. https://www.nasdaqtrader.com/content/ProductsServices/Trading/OrderTypesG.pdf
4. U.S. Securities and Exchange Commission. Regulation NMS, Rule 611 Order Protection Rule. https://www.sec.gov/rules/final/34-51808.pdf

Disclaimer

This article is educational content only and is not financial advice. Nothing here is a recommendation to buy, sell, or hold any security. Consult a licensed advisor before making investment decisions.