Mark Zuckerberg, chief executive officer and founder of Facebook Inc., left, and Reed Hastings, president and chief executive officer of Netflix Inc.

The new S&P 500 communication services sector , which now includes Facebook , Alphabet and Netflix , started trading Monday as a part of the largest reshuffling ever for the stock market's sector classifications.

"The historical risk-adjusted return profile of Comm Services will be among the best in the S&P 500 ... The new Comm Services sector will also offer growth at a reasonable valuation," Goldman's chief U.S. equity strategist, David Kostin, said in a note to clients Friday. "We recommended investors overweight Info Tech and Comm Services and underweight Consumer Discretionary."

Kostin said the new communication services sector had nearly two times the risk-adjusted return of the previous telecom sector in the current bull market run. He noted the reclassified sector's components have returned 17 percent annually since 2009 versus the old telecom's 9 percent annual return for the same time period.

The strategist also said the new sector is estimated to deliver the second-highest sales growth in the S&P 500 at 9 percent next year versus 6 percent for the general market.

For investors who want to take advantage of Goldman's bullish call, the Communication Services Select Sector SPDR Fund (XLC) tracks the performance of Communication Services Select Sector Index.