| Symbols | Variables | Interpretation |
| CS | Credit spreads | The difference between the coupon rate and the yield to maturity of Treasury bonds |
| ACQUI | M & A strategies | The ratio of M & A transaction value to total assets |
| LnASSET | Company size | The natural logarithm of the total amount of assets |
| LEVER | Leverage level | The gearing ratio is the ratio of total liabilities to total assets |
| ROA | Profitability | Net asset interest rate is the ratio of net profit to average total assets |
| CURREN | Solvency | The current ratio is the ratio of current assets to current liabilities |
| TERM | Bond maturity | The maturity period of the bonds issued by the company |
| TURN | Bond liquidity | The turnover rate of the bond on the first day of listing |
| LnGDP | Economic situation | The natural logarithm of GDP |