1. Carvana joins the S&P 500 on December 22. 2. BofA lifts Carvana's price target to $455 from $385. 3. Shares surged nearly 117% this year, outperforming the S&P 500. 4. Analyst sees Carvana surpassing CarMax in sales by 2026. 5. S&P upgrades Carvana's senior secured and unsecured debt ratings.