Individual investors have been snapping up stocks at the fastest pace on record as U.S. equity markets have charged higher to start the year. Over the past month, retail investors funneled an average of $1.51 billion each day into U.S. stocks, the highest amount ever recorded, according to data from research firm VandaTrack published Thursday. "With recent surveys showing the institutional investor community remaining broadly bearish on stocks, it would be unwise to underestimate the importance of the retail cohort," strategists at VandaTrack said in a note.