Again, there is no guarantee in technical analysis and all measures have their own merits and limitations. The trend analysis is no different. Similar to support and resistance, trends are not guaranteed to continue to hold. That’s why they are normally further classified into short-, medium-, and long-term trends so as to make the approach more granular. Trends can and do change and that is what you must keep an eye on as it allows you to really pre-empt the market and take positions before the trend actually manifests. But unless something happens to change the market behaviour then the trend is likely to continue. The golden rule of thumb is quite clear when it comes to up trends and down trends. As a trader you must buy stocks on an uptrend and either avoids stocks in a downtrend or look to take calibrated short positions.