Greenbrier Companies (GBX Quick QuoteGBX - Free Report) reached a significant support level, and could be a good pick for investors from a technical perspective. Recently, GBX broke through the 20-day moving average, which suggests a short-term bullish trend.

The 20-day simple moving average is a popular investing tool. Traders like this SMA because it offers a look back at a stock's price over a shorter period and helps smooth out price fluctuations. The 20-day can also show more trend reversal signals than longer-term moving averages.

Similar to other SMAs, if a stock's price moves above the 20-day, the trend is considered positive, while price falling below the moving average can signal a downward trend.

GBX could be on the verge of another rally after moving 5.5% higher over the last four weeks. Plus, the company is currently a Zacks Rank #1 (Strong Buy) stock.

Once investors consider GBX's positive earnings estimate revisions, the bullish case only solidifies. No earnings estimate has been lowered in the past two months, compared to 2 raised estimates, for the current fiscal year, and the consensus estimate has increased as well.

Investors may want to watch GBX for more gains in the near future given the company's key technical level and positive earnings estimate revisions.