Nasdaq - which was up 0.8% at one point this morning - legged lower after Jeff Gundlach's Facebook comments but has just tumbled back below Friday's lows... The specific catalyst for this latest plunge is unclear for now... The S&P and Dow are back in the red for 2018... The 10Y Yield is not directly driving this latest leg... And the Dollar made no reflexive move as stocks plunged...