If you haven't changed your password since 2013 and/or you use the same password for you online bank and credit card accounts as you do for yahoo mail...then yes, you are toast.
You realize the hack came in 2013...and yahoo just reported it. It's a billion accounts and it was 2 and a half years ago. I've changed my password at least 6 times since then, just because it's something I do. I also manage credit blocks on my ID's quarterly. Every financial account I have (banks, credit cards, investment firms) - I have changed those passwords at least 6 times since 2013 and those passwords are never the same as my email passwords.