Asif is a fund manager with a share portfolio currently valued at $1 billion under management. He considers that the share market is much over-priced and fears a sharp downturn of 20% in the market by June 2022, which will badly affect his share portfolio’s value and performance, which he wishes to protect. He seeks your advice as to whether he should take a short position in futures or buy a put option, each with an exercise price of $1 billion (the current value of his share portfolio). 

Explain each of the two strategies, and state your recommendation which Asif should follow, with reasons.