I logged into my brokerage account this morning, and found a stock I didn't recognize in my portfolio, 7 shares of Citadel Broadcasting (CDL).  I immediately thought WTFHAX!  I quickly hopped over to the account history page to see when this happened, and quickly learned it wasn't a hacker.  Apparently it's the result of Walt Disney selling ABC Radio to Citadel.  Disney shareholders received 0.0768 shares of Citadel for every share of Walt Disney Company.

CDL is already down $2.13 a share, 25.76%.   Gee, thanks, guys.  Edit:  CDL was also responsible for the mysterious $17.22 dividend payout I'd received that morning.  That explains the massive drop in share price.