Shares of UnitedHealth Group Inc. UNH, +0.38% slipped 0.2% in premarket trading Friday, after the health insurer reported higher-than-expected fourth-quarter medical costs, but earnings that beat forecasts. Net income rose to $5.46 billion, or$5.83 a share, from $4.76 billion, or$5.03 a share, in the year-ago period. Excluding nonrecurring items, adjusted earnings per share of $6.16 beat the FactSet consensus of$5.98. Revenue grew 14.1% to $94.43 billion, well above the FactSet consensus of$92.13 billio ...