FYI: 2018 certainly proved to be a turbulent period for equities, and the market was especially volatile in the fourth quarter, effectively wiping away all the gains that the S&P 500® had generated in the first three quarters of the year. Overall, the S&P 500 returned -4.38% in 2018. Despite landing in negative territory, the S&P 500 still performed better on a relative basis than its mid-cap or small-cap peers
Regards,
Ted
http://www.indexologyblog.com/2019/02/04/sp-500-performance-in-2018-how-much-does-size-matter/