Liquidity
West Pharmaceutical Services, Inc. trades about $257M a day, which puts it in the good liquidity tier. At that depth the model estimates a quoted spread of 8.68 bps, so a market order pays roughly half of it on the way in, and again on the way out. An order stays below 1% of a normal day's trading up to about $2.6M.
Volatility and risk
Daily volatility is around 1.47%, which is moderate for a stock. On a $10,000 position, the 1-day value at risk at 95% is about $242: on one trading day in twenty, a loss larger than that should be expected. Volatility also widens spreads, which the cost estimate above already includes.
How these figures are estimated
Spread: PreTrAIde's liquidity-tier model (average daily trading value) with a volatility uplift and a one-tick floor. Market impact: an Almgren-Chriss-style model on the order's share of daily volume. VaR: 1.645 × daily volatility. Inputs are 30-day average volume and recent price range. These are estimates, not quotes: the real cost depends on the market when the order is placed. PreTrAIde Methodology: How a Pre-Trade Analysis Is Computed