Stocks ended slightly lower Friday, but enjoyed their best monthly gain in four years in October. Average earnings above estimates, stabilizing oil prices, and accommodative global central banks have helped push equities back to near record highs. AbbVie (ABBV) rose as quarterly sales were boosted by strong demand for its treatment for arthritis and psoriasis. The drugmaker has also been developing a pipeline of medicines to treat maladies including leukemia. Crude oil settled at its best level since mid-October after the number of active rigs in the U.S. dropped over the past week. West Texas Intermediate crude was up 4.5% for the week and has risen 3.3% since the beginning of the month.