NEW YORK ( TheStreet) -- The third week of earnings season is now upon us, and investors appear to be bracing for more "Chipotle-esque" surprises.But if they were paying enough attention, they would have realized that Chipotle's ( CMG) results were not much of a surprise at all. While earnings can be an excellent time to buy undervalued stocks, on the flipside, the slightest miss in execution will punish those who are priced for perfection, as was the case for Chipotle. This punishment does not necessarily mean that the company is suddenly worse than prior to the announcement. It does, however, bring to the forefront one of the most important aspects of investing: valuation. In this article, we will to look at four stocks that are currently trading at valuation levels that suggest buying and selling. We are buying McDonald's ( MCD), Halliburton ( HAL) and Texas Instruments ( TXN), while placing a sell order on Netflix ( NFLX). Let's look at the case for each one and see if you agree.