Introducing Price Dynamics in a Markovian Limit Order Market for after-work quants

Takeaway. Short-term mid moves can be tied to queue sizes at the best bid/ask: when a queue depletes, the mid jumps—so a reduced Markov model of top-of-book queues becomes a price-dynamics engine.

Price Dynamics in a Markovian Limit Order Market (Rama Cont, Adrien de Larrard, 2011) is a favourite after-work "first serious LOB model" paper.

Fit for learners: Reduced Markovian LOB model linking queue sizes at the best quotes to short-term midprice dynamics.

This Hub note is a plain-language intro. Not investment advice. Pair with Gould et al. LOB survey.

The problem

Full LOB state is huge. Learners need a minimal stochastic object that still explains why mids tick when liquidity at the touch disappears.

The idea / core intuition

• Track mainly the sizes of the best bid and ask queues (plus event intensities).
• Arrivals, cancels, and market orders change those queues; hitting zero moves the mid to the next level (in the reduced story).
• Markov structure makes waiting times and move probabilities discussable without a 50-level simulator.
• Empirically motivated: imbalance and queue depletion matter for ultra-short horizons.

Open the PDF for formal generators and results. Educational use only.

Why after-work Python learners care

Queue imbalance features appear in countless ML microstructure notebooks. This paper explains why best sizes belong in your feature list.

Tiny evening exercise: simulate two integers (bid_size, ask_size) with random +1/−1 events; when one hits 0, bump mid ±1 tick and reset that queue to a random refill—plot mid path for 200 events.

One-evening reading checklist

1. State variables: what is kept vs ignored vs full book.
2. How a midprice change is triggered in the model.
3. Role of intensities / Poisson-type events (intuitive level).
4. One sentence: imbalance → short-horizon direction risk (model sense).

Download PDF

Download PDF

Landing: arXiv:1104.4596

Important disclaimer

Not investment advice. This Hub note is educational only. The paper is research—not a licence to trade, quote, or execute with real capital.

What this is not

• Not CEF / subsidy framing
• Not Quant or Macro course CTA
• Not a broker / signal-group pitch

Next step

Single course CTA: SoloQuant Academy's Introduction to Python Programming—get comfortable with functions, files, and plots first; then these microstructure PDFs become much less scary.