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How is Interest Calculated on Short Selling?

Published in Finance 2 mins read

Interest on short selling is calculated based on the borrow rate of the security you're shorting. This rate represents the cost of borrowing the security from a lender.

Here's how it works:

  • Borrow Rate: The borrow rate is typically expressed as an annual percentage. It reflects the supply and demand for the security.
  • Interest Calculation: The interest you pay is calculated based on the borrowed shares, the borrow rate, and the duration of the short position.
    • Interest = (Borrow Rate x Number of Shares x Number of Days) / 365
  • Example: If you short 100 shares of a stock with a borrow rate of 5% for 30 days, the interest would be: (0.05 x 100 x 30) / 365 = $0.41 (approximately).
  • Broker Fees: Your broker may also charge a small fee for facilitating the short sale.

Important Considerations:

  • Borrow Rate Volatility: Borrow rates can fluctuate significantly depending on factors such as market demand for the security, the lender's availability, and the time of year.
  • Hard-to-Borrow Stocks: Some stocks are harder to borrow, leading to higher borrow rates.
  • Interest Cost Impact: The interest cost on short selling can significantly impact the profitability of your trade.

In summary, the interest on short selling is determined by the borrow rate, which reflects the cost of borrowing the security. This interest cost is a crucial factor to consider when making short-selling decisions.

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