"市势疲弱" can be translated into English as "the market is weak" or "the market trend is sluggish".
"The market is weak" directly conveys the idea of a market lacking strength or vitality.
"The market trend is sluggish" emphasizes the slow or unresponsive nature of the market movement, which also aligns with the meaning of "市势疲弱".
Both expressions are commonly used in financial and economic contexts to describe a market that is not performing well or is showing signs of weakness.