Shares of Allergan (AGN) - Get Report saw an increase in volatility and range in 2015 which eventually led to the formation of a wide triple top and the transition from a six-year uptrend to a one-year downtrend.

On Friday, Jim Cramer and Jack Mohr of the Action Alerts PLUS portfolio wrote that Allergan stock had been hurt along with the rest of its sector. "The biotech sector as a whole remains hostage to any political commentary that can arise on any day at any time," they commented.

However, "The company trades at the cheapest valuation of all the major drug stocks based on growth rate," Cramer and Mohr noted. They have a price target of $270 on the stock.

Allergan is a holding in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer buys or sellsAGN? Learn more now.

The weekly chart shows the topping pattern and the period of lower highs and lower lows that followed, taking over 41% off the share value.

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There is not very much in the way of long-term support on this chart, aside from the May low this year in the $195 area, which has been sticky enough to slow the decline over the last two months.

That short-term consolidation has formed a triple bottom on the daily chart just below the $195 level, and a break above that resistance has the potential to be volatile and profitable.

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The daily chart shows the two lows in November and the low this month, forming the bullish triple reversal pattern, and the consolidation just below $195 resistance. The price range contraction has taken the Bollinger bandwidth indicator to its lowest or tightest reading since August, after which the 50-day moving average was broken to the downside and the stock price continued lower.

Moving average convergence/divergence has made a bullish crossover and is tracking higher, and the stochastic oscillator is above its center line.

The most bullish indication on the chart, however, is the increase in positive money flow. The accumulation/distribution line has crossed above its signal line. Chaikin money flow, which uses accumulation/distribution as its base line but averages it over 20 periods, has been improving since the November low reading.

These indicators suggest that there is renewed buying interest in the stock at current levels.

Allergan is a buy after an upper candle close above the $195 level using a trailing percentage stop.

This article is commentary by an independent contributor. At the time of publication, the author held no position in the stocks mentioned.