Summary: The S&P 500 and Dow Jones Industrial Average backed off from records set at beginning of week. Crude oil stumbled into bear market territory, having fallen just over 20% below a 52-week high set in late February. House Speaker Paul Ryan expects tax reform by year's end. At an event Tuesday, he called on Congress to seize "once-in-a-generation moment" Chipotle Mexican Grill fell after warning of tighter profit margins in current quarter. Marketing and promotion costs expected to climb by 20 to 30 basis points in the second quarter. Cable companies, including Comcast Corp. and Charter Communications Inc. , were under pressure, MoffettNathanson's Craig Moffett downgrades sector to neutral from overweight
