Stocks extended their rally in midday trading Tuesday for the most part. The Dow industrials are shooting past 18,000. The S&P 500 is at its intraday record. The Nasdaq, however gave up its initial gains and is now in the red. Biotech names are pressuring the Nasdaq lower. Both Celgene (CELG) and Gilead (GILD) are trading down 5%. Investors are digesting a ton of fresh economic data, including sales of new homes falling for a second straight month. Sales dropped 1.6% in November, economist were expecting a rise. But a positive sign for retailers this holiday season, consumer spending was up 0.6% last month, exceeding expectations. The final reading for the University of Michigan sentiment index for December also came in at 93.6, its best reading in nearly 8 years fueled by cheaper gas prices.