Some perspective
I came across the chart and it's worth sharing because it's a reminder ahead of Powell's testimony on Wednesday that tapering is much feared because of the words 'taper tantrum' but actual event has grown in stature more than it deserves.
The tantrum itself came in the summer of 2013 after signals from Yellen but it followed a rapid run-up in stocks. At the time, a taper wasn't surprising and I'd argue that it was a standard drop that in the ebb-and-flow of markets at the time.
Anyway, you can make your own conclusions from the chart. I'd also point out that once something becomes 'known' and 'talked about' like a taper tantrum, the effects of it are invariably diminished.
Powell speaks at noon ET (1600 GMT) on Wednesday.