NEW YORK (Reuters) - The summer roller-coaster in two of the four big-cap ‘FANG’ names - Facebook Inc, Amazon.com Inc, Netflix Inc and Google-parent Alphabet Inc - has led to a shift, albeit slight, into value stocks.

Traders work on the floor of the New York Stock Exchange (NYSE) in New York, U.S., August 17, 2018. REUTERS/Brendan McDermid

In the last four weeks, the Russell 1000 Value Index has outperformed its growth counterpart by the largest monthly margin since September 2017, thanks in part to stumbles in Facebook and Netflix shares that stemmed from slowing user growth. Moreover, disappointing second-quarter results have reignited fears the tech giants, which have been responsible for much of the equity market’s gains this year, are becoming vulnerable.

Funds that follow a value investing strategy attracted $791 million in July and August, reversing a trend in the first half of the year, when investors withdrew $4.9 billion from such funds, according to Thomson Reuters Lipper data.

“The (economic) outlook is significantly better than it was six months ago, and yet stock prices haven’t gone up very much. As a result, there are more value opportunities,” said Charlie Bobrinskoy, vice chairman at Ariel Investments in Chicago.

Value stocks are even more attractive on a relative basis, fund managers said. The gap between forward price-to-earnings ratios for the two categories has swelled to the widest level in the past 15 years, Reuters data showed.

“You’re starting to see the market differentiate,” said Drew Wilson, investment research analyst at Fenimore Asset Management in Cobleskill, New York.

The growing difference in earnings multiples gives buyers of value stocks an added margin of safety, which was rare when they were tighter, Wilson said.

Value investors also say undervalued companies can be found in sectors such as energy, healthcare and financials.

“If you’re trying to find companies that are trading for less than 15 times earnings or less than two times book value, you end up with a lot of banks and a fair number of insurance companies as well,” said Bobrinskoy.

Fenimore’s Wilson has been taking advantage of value stocks that have come under selling pressure in the wake of threats from disruptive companies like Amazon.com.

“Any time Amazon even looks the way of an industry, it sells off,” he said. Wilson said he has found buying opportunities in companies pressured by the online retail giant, such as Dollar General Corp and AutoZone Inc, which have shown resilience to such competition.

Strategists said macroeconomic trends have also lined up to give value a boost.

Higher levels of gross domestic product growth and more widely shared earnings growth among companies should help value stocks, said Steven DeSanctis, SMID-cap strategist at Jefferies in New York.

DeSanctis said he expects value to outperform growth in the second half of 2018.

Rising interest rates likewise aid many value stocks that languished in the slow-growth, low-yield environment of years past that favored growth-oriented companies, said Charlie McElligott, head of cross asset macro strategy at Nomura.

Mutual fund managers who adhere to a value strategy said they were cautiously hopeful that a rotation was in its early stages.

Investors have pulled cash from value-oriented mutual funds for seven of the past 10 years, chasing gains by growth stocks and shifting to lower-cost exchange traded funds, according to data from Thomson Reuters Lipper.

More than twice as many value funds have closed than have launched during that period, Lipper said.

Value stocks, however, tend to outperform growth over the long term, prompting many to wonder how long the current rout can last.

“These style cycles tend to come and go,” said Aaron Anderson, senior vice president of research at Fisher Investments in Woodside, California.

“Eventually you get to some extreme where people have written off value entirely, and that’s probably where you get a reversal.”