Shares of Coca-Cola (KO) - Get Report were under pressure for nearly all of Tuesday's session. The stock closed with a 1.5% loss as downside volume picked up noticeably ahead of Wednesday's earnings report.

This is a sharp reversal from the bullish action last week. As last week came to an end, Coca-Cola appeared to be on the verge of a breakout. The stock was beginning to put some distance on a key overhead trend line that linked the April and June highs.

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Immediately after the Brexit sell off Coke bounced back. By the second week of July, the stock was setting up for a nice run but was unable to move past the $46 area. This heavy resistance zone, which is marked by a still unfilled breakdown gap from late April, also capped the May and June highs.

As Coca-Cola fades away from this area again this week, overhead pressure here is building. In the near term, more downside is likely as another pullback develops.

Patient Coke bulls should view lower prices as a buying opportunity. The stock has layers of support underneath. A drift down to the $44 area will retest the stock's 200-day moving average. This important long-term indicator did a great job of limiting the losses in June and January. Coca-Cola has not closed below its 200-day since October of last year. Also in this zone is the stock's May low. This is the upper band of a very low-risk buy zone. A close below the April spike low of $42.85 would be a clear warning sign that the overhead pressure has taken control.

Disclosure: This article is commentary by an independent contributor. At the time of publication, the author was long KO.