On October 23 an investor holds 80,000 shares of a certain stock.

The market price is $12 per share.

The investor wants to double the market exposure of her shares over the next month and decides to use the December S&P/TSX 60 index futures contract.

The current level of the index is 700 and one contract is for the delivery of $200 times the index.

The beta of the stock is 0.5.

The initial margin for the S&P/TSX 60 index futures contract is $6,000 per contract and the maintenance margin is $4,000 per contract.

What change in the level of the S&P/TSX 60 index will trigger a margin call for the investor?