Arguably, one area of concern is technology, haunted by memories of the late-1990s collapse in sector shares after a period of exuberant valuations.
This year, U.S. tech shares have risen nearly 40 percent and firms such Facebook and Google trade at more than 30 times forward earnings. Broader U.S. stocks trade 18 times earnings, versus a 10-year average of 14.3, Thomson Reuters Datastream shows.
But the innovative, digitized nature of many modern firms means historical references may no longer apply, said Wayne Bowers, who helps oversee about $1 trillion at Northern Trust Asset Management.
"You can argue...the market does justify the high level of valuations," Bowers told the summit.
Bumpy 2018
BAML called the early-November equity wobble a "dress rehearsal," and indeed, some investors suggested 2018 could prove a "bumpy" one if central banks in the United States and Europe end up sucking more liquidity from markets than expected.
With the U.S. Federal Reserve seen raising rates twice and the European Central Bank planning to halve bond purchases, the "monetary component" in the equity rally will diminish, predicted Pascal Blanque, who oversees 1.4 trillion euros at Europe's largest asset manager Amundi.
"From now, you can count less on this (monetary policy), meaning that earnings growth will prove even more critical," Blanque said.
"Which for the moment is ok," he added.
This article was provided by Reuters.