NOOP is the NASDAQ Official Opening Price. When the stock market opens at 9:30 AM EST the NASDAQ stock market must designated the opening prices for each security that trades on the NASDAQ stock market.
Applying "NOOP" to Securities Exams:
Because there is no centralized location where securities trade on the NASDAQ, the NASDAQ opens its securities with an opening cross. During this cross orders to buy and sell the securities are paired off and the NOOP or NASDAQ Official Opening Price is determined.