stock-liquidity

Stock Liquidity — Stock Liquidity Analysis Skill

Skill Overview

Stock Liquidity is a professional tool for analyzing stock liquidity. Using data from Yahoo Finance, it helps you assess trading costs and liquidity risk, including key metrics such as bid-ask spread, volume analysis, estimated market impact, and turnover rate.

Use Cases

1. Liquidity Assessment Before Trading

Before buying or selling a stock, understand its liquidity conditions to judge how easily the trade can be executed and the potential slippage costs you may face. This is especially suitable for evaluating the feasibility of trading small-cap stocks, illiquid or less-followed stocks, or large orders.

2. Trading Cost Analysis

Calculate implicit trading costs such as bid-ask spread and market impact to help you more accurately evaluate investment returns. For frequent traders or quantitative strategy backtesting, precise cost estimation is crucial.

3. Liquidity Comparison Studies

Compare liquidity differences across multiple stocks to select the best candidates for your trading size and style. Supports batch comparison of liquidity metrics for large-cap, mid-cap, and small-cap stocks.

Core Features

1. Liquidity Dashboard

Provides a comprehensive overview of a stock’s liquidity, including current bid-ask spread, average daily trading volume (ADTV), dollar trading volume, turnover rate, and the Amihud illiquidity ratio, among other core metrics. It also automatically assigns a liquidity rating (extremely high, high, medium, low, extremely low).

2. Market Impact Estimation

Based on the square-root market impact model, it estimates the potential price impact of different order sizes. Helps you determine whether your position size is reasonable and avoid overly high slippage costs caused by holding a position that is too large.

3. Trading Volume Depth Analysis

Analyzes volume trends, relative volume (RVOL), intraday volume distribution, and high/low volume days to help you identify abnormal trading activity and patterns of liquidity changes.

FAQs

What does stock liquidity mean?

Stock liquidity refers to how easy it is to buy and sell a stock without significantly affecting the price. High-liquidity stocks (e.g., Apple, Microsoft) typically have a small bid-ask spread and large trading volumes, allowing you to transact at prices close to the market at any time. Low-liquidity stocks may have a larger bid-ask spread and smaller trading volume, and large trades can cause substantial price fluctuations.

How can I tell if a stock is liquid?

You can assess liquidity using these key indicators: bid-ask spread (the smaller the better; typically under 0.1% is considered good), average daily trading volume (the larger the better; large-cap stocks often trade millions of shares per day), dollar trading volume (more than $100 million indicates high liquidity), and turnover rate (daily turnover above 1% is relatively active). This skill’s liquidity dashboard automatically calculates these metrics and provides a rating.

Do large orders affect the stock price?

Yes. The larger the order size relative to the stock’s average daily trading volume, the greater the potential impact on price. This skill uses the square-root market impact model to estimate that impact. For example, if a stock trades 1,000,000 shares per day and you trade 10,000 shares (1% of daily volume), the model estimates the price impact to be approximately equal to the stock’s daily volatility multiplied by 0.1. For high-liquidity stocks, the impact may only be a few basis points; but for low-liquidity stocks, it could reach dozens or even over 100 basis points.

How much does the bid-ask spread affect trading costs?

The bid-ask spread is a direct component of trading costs. If you buy at the market and then sell immediately, you will lose the amount of one bid-ask spread (buy at the higher price and sell at the lower price). For example, if a stock’s buy price is 100 and sell price is 100.10, the spread is 0.10, so your immediate loss is 0.10—equivalent to a 0.10% cost. For frequent traders, these costs accumulate quickly.

What is the data source for this tool?

This skill uses Python’s yfinance library to fetch free public data from Yahoo Finance. Note that this data is about 15 minutes delayed and does not provide complete Level 2 order book data. For real-time trading decisions, it is recommended to use professional market data sources.

What is the Amihud illiquidity indicator?

The Amihud indicator measures the degree of price impact per unit of trading volume. Its formula is the average of |daily returns| divided by the average of dollar trading volume. A higher value indicates the stock is less liquid (greater price fluctuation for the same trading volume). This metric is widely used in academic research and institutional investment analysis and is an important reference for assessing liquidity risk.

Which markets are supported?

In theory, it supports all markets covered by Yahoo Finance, including U.S. stocks, Hong Kong stocks, and A-shares. However, note that data quality and update frequency may differ across markets, and bid-ask spread data may be incomplete in some cases. U.S. stock data has the highest coverage and accuracy.