What it is:
How it works (Example):
For example, let's assume that on June 1, the price of gold is $1,000 an ounce at the end of the trading day. Using the call rule, the opening price of gold must be $1,000 an ounce on June 2 (or the next trading day if June 2 falls on a weekend or trading holiday).
Why it Matters:
Thought it seems intuitive that yesterday's closing price should be today's opening price, it wasn't always that way. The Commodity Futures Trading Commission (CFTC) established the call rule because traders were making private bids among each other overnight, which wildly altered opening prices the next day. In 1906, the Chicago Board of Trade (CBOT) adopted the rule, and the Supreme Court affirmed the legality of the call rule in 1918.