Large-Tick Versus Small-Tick Stocks
When the minimum price increment is large relative to the stock's typical spread, the book behaves completely differently — pinned spreads, deep queues, and a microstructure of its own.
Prerequisites: Depth At Touch And The Shape Of The Book
Every exchange sets a minimum price increment — a tick. Whether that tick is "large" or "small" isn't about its absolute size in cents; it's about its size relative to the spread the stock would naturally trade at if there were no tick constraint at all.
A large-tick stock is one where the tick is big enough that the natural spread would be smaller than one tick, so the spread gets pinned at exactly one tick almost all the time. A small-tick stock has room for the spread to move freely across many ticks, and it usually does.
A worked comparison
Stock X trades around $8.00 with a 1-cent tick. Its natural, tick-free spread would be roughly half a cent — smaller than the minimum increment — so in practice the quoted spread is always exactly 1 cent: 8.00/8.01, all day, every day. Because the spread can't compress any further, all the competition for being first happens in queue position instead of price: everyone posts at the same two prices, and the size stacked at the touch grows enormous — often thousands of shares — because that's the only lever left.
Stock Y trades around $400 with the same 1-cent tick. A cent is a tiny fraction of the price, so the spread roams freely: 400.03/400.05 one moment, 400.11/400.14 the next. Traders compete on price, not queue position, because undercutting by a cent is cheap and effective. Depth at any single level stays comparatively thin, since there's no reason to stack size at one price when a one-tick improvement is always available.
"Large-tick" and "small-tick" describe the tick relative to the spread, not the tick in absolute cents — a name is large-tick if it always quotes exactly one tick wide.
Why it matters. In a large-tick name, queue position is everything: two orders at the same price fill in strict time order, so Queue Position and Priority and the value of arriving early dominate strategy. In a small-tick name, price competition dominates instead, and undercutting by a tick to jump the queue is usually cheap enough to be worth doing constantly. Execution algorithms, market-making models, and even simple limit-versus-market decisions need to be tuned differently for each regime — a strategy calibrated on a large-tick book will misbehave badly if pointed at a small-tick one.
Whether a name is large- or small-tick can change over time as price drifts — a stock climbing from $8 to $80 gradually crosses from large-tick to small-tick behaviour with no change in the exchange's tick rules at all, and a model trained on old data can quietly go stale.
Practice in interviews
Further reading
- Eisler, Bouchaud & Kockelkoren (2012), The Price Impact of Order Book Events: Market Orders, Limit Orders and Cancellations
- Dayri & Rosenbaum (2015), Large Tick Assets: Implicit Spread and Optimal Tick Size