Baidu's (NASDAQ:BIDU) stock recently hit a two-year high after a series of positive developments. First, the company's third-quarter report in November suggested its core advertising business was stabilizing, which sparked several upgrades from analysts. Chinese regulators then drafted new antitrust rules that seemingly affected Tencent (OTC:TCEHY) more than Baidu. Baidu also boosted its existing buyback plan from $3 billion to $4.5 billion this month, and a recent Reuters report suggested it might start producing its own electric vehicles to complement its driverless efforts. Those headlines all buoyed Baidu's stock -- but should investors chase its recent rally, or take profits instead?