| Variable symbol | Variables | Definition |
| Dependent variable |
| |
| MAR | Adjusted IPO underpricing rate | (closing price − issue price)/issue price − current market rate of return |
| Independent variable |
| |
| VC | Venture capital | Dummy variable; the company’s IPO has a VC holding of 1, otherwise 0. |
| TECH | technology | Dummy variable; the company was identified as a high-tech firms indicating that the demand for technology is high, recorded as 1, otherwise 0. |
| RD | R & D input | Ratio of R & D expenditure to main business income in the year before listing |
| Control variable |
| |
| Age | firm age | Ln(listing date-establishment date) |
| Delay | Listing interval | Ln(days between the listing date and the issue date) |
| LEV | Financial risk | Asset-liability ratio for the year prior to listing |
| LOTT | lottery | Ratio of the number of shares issued and the number of shares purchased |
| ROE | Return on equity | Weighted return on equity in the year prior to listing |
| Scale | Firm scale | Ln(Total assets at the end of the year prior to listing) |
| Size | Financing scale | Ln(scale) |
| TR | Turnover rate | Turnover rate on listing date |
| UR | Underwriter reputation | Dummy variable; IPO business of leading underwriter is ranked top 10, recorded as 1, otherwise 0 |
| Year | Year of listing | Control variable of the year; it is recorded as 1 in the current year, otherwise 0 |
| IND | industry | Control variable of the industry; it is recorded as 1 of the industry, otherwise 0 |