  The trade size $\omega$ has direct impact on the price formation of the stock
traded. Econophysical analyses of transaction data for the US and Australian
stock markets have uncovered market-specific scaling laws, where a master curve
of price impact can be obtained in each market when stock capitalization $C$ is
included as an argument in the scaling relation. However, the rationale of
introducing stock capitalization in the scaling is unclear and the anomalous
negative correlation between price change $r$ and trade size $\omega$ for small
trades is unexplained. Here we show that these issues can be addressed by
taking into account the aggressiveness of orders that result in trades together
with a proper normalization technique. Using order book data from the Chinese
market, we show that trades from filled and partially filled limit orders have
very different price impact. The price impact of trades from partially filled
orders is constant when the volume is not too large, while that of filled
orders shows power-law behavior $r\sim \omega^\alpha$ with $\alpha\approx2/3$.
When returns and volumes are normalized by stock-dependent averages,
capitalization-independent scaling laws emerge for both types of trades.
However, no scaling relation in terms of stock capitalization can be
constructed. In addition, the relation $\alpha=\alpha_\omega/\alpha_r$ is
verified, where $\alpha_\omega$ and $\alpha_r$ are the tail exponents of trade
sizes and returns. These observations also enable us to explain the anomalous
negative correlation between $r$ and $\omega$ for small-size trades. We
anticipate that these regularities may hold in other order-driven markets.
