Hedging with Index Futures. Jill manages a stock portfolio valued at $50 million on August 15. The beta of her portfolio is 0.9. Jill wants to hedge her portfolio's market risk for the next three months, using S&P 500 index futures. The December index futures is 1,150 on August 15 (each index point is worth $250). The December futures will expire in four months. The dividend yield of the S&P 500 is 2.5% and the riskless interest rate is 1%, both per annum. (a) To fully hedge her portfolio, how many of the December S&P 500 futures contracts should Jill long or short? (b) Three months later, on November 15, Jill's portfolio is valued at $45 million while the December S&P 500 futures is 1,020. What has been the net profit (loss) of her hedged portfolio in part (a)? (c) Suppose on August 15, the spot S&P 500 index is also 1,150 (the same as its December futures). Is there an opportunity for index arbitrage on this day? Why?