Liquidity Stratification Pricing Factor

Hypothesis
During periods of liquidity tightening or market stress, investors' preference for asset liquidity increases sharply, leading to an intensified phenomenon of liquidity stratification. High-liquidity stocks experience relatively smaller declines due to a "liquidity premium," while low-liquidity stocks are sold off significantly due to a "liquidity discount." When market stress eases and the liquidity environment shifts towards easing, previously overly discounted low-liquidity stocks often exhibit stronger mean reversion and generate more substantial rebounds. Conversely, in the initial phase of a shift from loose to tight market liquidity, high-liquidity stocks may demonstrate stronger defensive characteristics.

Implementation Plan
Construct a comprehensive liquidity measurement indicator incorporating trading volume, turnover rate, bid-ask spread, and the Amihud illiquidity ratio. Use a time-series market regime identification operator (e.g., based on thresholds for market breadth, monetary conditions index, or volatility index VIX) to determine the prevailing "liquidity regime" of the market. During phases identified as a transition from "tight" to "easy," apply positive weights to the portfolio of stocks with the worst prior liquidity (bottom 20% based on the composite indicator). In the initial phase of liquidity "tightening," apply positive weights to the portfolio of stocks with the best liquidity (top 20%). Utilize cross-sectional ranking and group assignment to construct the investment portfolio.

Alpha Factor Optimization Suggestions
Pure liquidity metrics can be strongly influenced by firm market capitalization and industry attributes. A two-step neutralization process is recommended: First, perform liquidity ranking within industries to eliminate differences in industry trading characteristics. Second, after factor construction, control for exposure to the size factor. Furthermore, introducing the "duration of liquidity shock" as a weighting parameter could help refine the strategy. Stocks that have endured liquidity pressure for a longer period could be assigned higher weights during the reversal phase to more precisely capture the rebound momentum following suppression.

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ts_product ts_zscore ts_mean  ts_scale  add  sign  subtract ts_delta ts_rank greater ts_av_diff ts_quantile ts_count_nans ts_covariance
ts_arg_min divide ts_corr multiply if_else ts_sum ts_delay group_zscore ts_arg_max ts_std_de ts_backfill
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