Those one billion Yahoo! users’ account information, which was stolen back in 2013, is now for sale on the computer underground market for a total of a little less than one million dollars.
So not only is the data currently in the hands of criminals and probably being utilized, but if you have not changed your passwords that were also similar to your Yahoo password, all your other accounts might be jeopardized.
And this is just the tip of the iceberg because not only were passwords taken, but so were security questions and answers. These are also reused by many of us throughout multiple accounts. So not only should you utilize a password manager and generator for your passwords, but also for security questions. At the very least, keep the passwords and answers in a simple spreadsheet. Remember, your security answer does not actually have to be Spot, your first pet. It could be jIes92#lf!FW.