The VIX is a one traditional way of measuring the fear in the markets!
"At the time of writing:
At-the-money put: SPY with strike price $120 Oct 11 trades between $5.43 (the bid) and $5.44 (the ask)
Deep out-the-money: SPY with strike price $92 Oct 11 trades between $.50 (the bid) and $.52 (the ask).
Not to be too technical, the value of American options - which can be exercised before expiration - is determined by using a binomial tree model that uses the following inputs..."
Read the rest of the analysis here.