Since the bottom of the bear run last month, bitcoin has seen several rallies that have continued along a generally positive trend. The figure above shows a trend of higher highs, higher lows and an upper/lower boundary that is converging. This type of price activity is called a rising wedge.
Coupled with this price growth is a trend of decreasing volume throughout the length of the wedge. A rising wedge is generally a bearish trend that shows weakening bullish pressure as each subsequent rally becomes smaller and smaller. As the price corrects, there are rallies that bring the price to new highs, but ultimately rally on smaller and smaller volume.
https://bitcoinmagazine.com/articles/bitcoin-price-analysis-there-may-still-be-some-life-these-exhausted-bulls/