1. Carvana shares rose 1.1% to $461.40, nearing $100 billion market cap. 2. S&P 500 inclusion on December 22 boosted stock gains by nearly 50%. 3. The stock surged 127% this year, outperforming the S&P 500. 4. Analysts caution about the stock's premium valuation despite growth. 5. A significant market change is anticipated following the S&P 500 inclusion.