Dow Theory identifies three types of market trends that describe how prices move over time: primary, secondary, and minor trends. These trends help investors understand the broader market direction and avoid being misled by short-term fluctuations.

The primary trend is the main, long-term movement of the market. It can last from several months to many years and represents the overall direction—either bullish (upward) or bearish (downward). In a primary uptrend, prices form higher highs and higher lows. In a primary downtrend, prices create lower highs and lower lows. This trend reflects the fundamental economic forces driving the market.

The secondary trend is a corrective movement within the primary trend. It typically lasts from a few weeks to a few months and retraces a portion of the primary move, often between one-third and two-thirds of it. For example, in a primary bull market, a secondary trend would be a temporary decline or correction before the upward movement resumes.

The minor trend is short-term and lasts from a few days to a few weeks. It represents daily market noise and small price fluctuations. According to Dow Theory, minor trends are less significant for long-term investors, who should focus mainly on identifying and following the primary trend.