legal ground
Article 13 of the Measures for the Administration of Stock Pledged Loans of Securities Companies
The stock pledge rate shall be agreed with the borrower by the lender according to the quality of the pledged stock and the borrower's financial and credit status, but the stock pledge rate shall not exceed 60% at most. The adjustment of the upper limit of pledge rate is decided by the People's Bank of China and China Banking Regulatory Commission.
Calculation formula of pledge rate:
Pledge rate = (loan principal/market value of pledged shares) × 100%.
Market value of pledged shares = number of pledged shares × average closing price of shares in the first seven trading days.