On July 1, an investor holds 50,000 shares of a certain stock. The market price is $30 per share. The investor is interested in hedging against movements in the market over the next month and decides to use the Sept Mini S&P 500 futures contract. The index futures price is 1,500 and one contract is for delivery of $50 times the index. The beta of the stock is 1.3. How many short Sept Mini SP500 futures does the investor need to hedge the market risk?