I'm stupid

In light of the plummeting stock market today (S&P 500 down 3.09%), I thought I might pick up some more stock at a potential bargain. Specifically, I was going to add some Bank of America (ticker symbol: BAC, down about 4.66% today). I already held a position with BAC and was going to add to it, but when I checked my brokerage account online today, it showed no BAC. I was a little confused until I looked at my execution history and realized that instead of buying more shares of BAC and doubling my position a couple weeks ago, I actually sold all my shares. Whoops. I felt kind of stupid, though the transaction didn't involve too many shares or too much money. Plus, it was actually a better move to sell than buy, since the share price has gone down about $3 since then. I'm not a big stock trader by any means and I view any trading I do as mainly an educational experience, so hopefully I learned something from this.