On Monday, Casella Waste Systems reached an important technical milestone, with its Relative Strength (RS) Rating entering into the 80-plus percentile with an upgrade to 82, up from 79 the day before.

When you're researching the best stocks to buy and watch, be sure to pay attention to relative price strength.

This exclusive rating from Investor's Business Daily identifies market leadership with a 1 (worst) to 99 (best) score. The rating shows how a stock's price performance over the last 52 weeks compares to all the other stocks in our database.

Decades of market research reveals that the stocks that go on to make the biggest gains tend to have an 80 or better RS Rating as they begin their biggest runs.

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Casella Waste Systems is now considered extended and out of buy range after clearing a 69.70 buy point in a first-stage cup without handle. See if the stock forms a new pattern or follow-on buying opportunity like a three-weeks tight or pullback to the 50-day or 10-week moving average.

Earnings growth decreased in the most recent report from 125% to -4%. But revenue gains moved higher, from 4% to 14%.

The company earns the No. 8 rank among its peers in the Pollution-Control industry group. G F L Environmental Inc and Republic Services are also among the group's highest-rated stocks.