Cramer says 4 things—including the tax overhaul—will continue to push stocks higher By: CNBC.com News January 08, 2018 at 18:14 PM EST Jim Cramer explained how index funds, stock shortages, tax cuts and low valuations all coalesce to drive stocks higher. Read More >> Related Stocks: 3M Co Caterpillar NVIDIA Corp Tesla, Inc. Wal-Mart Stores, Inc.