I've often wondered if a down period has to at least last a certain amount of time to be called a correction. With the Excel spreadsheet I use to track my investments, I used to track the peaks and lows, although I'd only save one data point for the month. But, starting in September of 2011, I simply saved the last data point for the month. That's probably smoothed out a lot of the turbulence, on my own timeline.
Anyway, the last thing that I would call a "correction", in my own experience at least, would be back in 2011. I hit a new peak on July 7, but by August 8 I was down 14.2%. That's simply a drop in net worth, and doesn't take into account additional investments. However, it represented a drop from around $659K to $565K, so anything else I put in that month wouldn't have swayed things much.
I haven't seen a drop of 10% or more since that period. However, if I only saved, say, the 7/31/11 and 8/31/11 data points, I wonder if that might have smoothed out even that drop?
FWIW, the most serious decline I've seen since that 7/7-8/8/11 period was in 2015. I had peaked in May, but by September was down about 7.5%. Again, that doesn't take into account additional investments, but that would've have been enough to sway the numbers.
I've heard though, that there was a 10% correction at some point in late 2015, and again in early 2016. For some reason, I'm recalling one in late 2014 as well, although the worst month-to-month decline my spreadsheet shows is 2.5%, from August to September 2014.
As for this most recent dip? Well, looking at it from January 31 through February 28, I only dropped 2.1%. I know that glosses over how turbulent that timeframe was, but even at the worst, I don't think I was down by 10%. Maybe 7-8%? March has been great, so far though. Yesterday's close puts me up about 4.2%, YTD. And unlike my other numbers, that's actually rate of return, rather than simply a rise in net worth. Of course, who knows...this "correction period" could just be getting started.