US STOCKS-Indexes lower as energy and industrials weigh
* Boeing biggest drag on Dow
* Crude oil prices continue to slide
* Investors prepare for "quadruple witching"
* Red Hat up after FY rev forecast increase
* Indexes down: Dow 0.79 pct, S&P 0.61 pct, Nasdaq 0.50 pct (Updates to open)
By Abhiram Nandakumar
Dec 18 (Reuters) - U.S. stock indexes were lower in early morning trading on Friday as crude oil prices headed for their third straight weekly loss on global oversupply concerns.
Trading was also set to be more volatile than usual on "quadruple-witching" Friday, when options on stocks and indexes as well as futures on indexes and single stocks expire.
"Everyone is worried about the $1.2 trillion options expiration that takes place today and you're going to see some jimmying and jammying around that," said Jeffrey Saut, chief investment strategist at Raymond James Financial in Florida. Continuación...