the truth is that some point depending on what the price is dictating one will either act in a bullish position or bearish position. though for me it is better to buy more because at a point when the price goes up one might be thinking the price might come down and be tempted to sell and one end up loosing when the price go up further again. but if one sell some at the point where one is thinking the price has reach the peak, when the price go up further you can now sell the remaining stock.