# Implied Volatility of the S&P Today

Suppose you're an investor and are curious what the market thinks the implied volatility of the S&P 500 is today. You know a few things:

• You can assume that every other investor is using Black-Scholes-Merton formula for pricing.
• You look a common ETF of the S&P 500, the SPY spider.
• Today it's priced at $216. • A European call option has a strike price of$210.
• To expire, there are 30 days left from today.
• The risk-free interest rate is 1.8%.
• The market is pricing this European call option at \$7.93.

What is the implied volatility?