Circle shares surged at the U.S. stock market open and briefly reached $140, with the stock earlier cited at $139.82, up 6.12%, and trading volume at $604 million. Later, according to msx data, the stock slipped back below $135 to trade at $134.3, reducing the session gain to 1.93%. The price action indicates that strong opening momentum gave way to a partial intraday pullback after heavy early trading.