Upstream catches aftermarket updraft, as Camp4 IPO gets muted reception

Two more IPOs late this week added to the body of evidence for which newly listed biotechs will capture investors’ demand, and which ones are a tougher sell.

Upstream Bio Inc. (NASDAQ:UPB), a developer of therapies in the closely watched inflammation/immune space, enjoyed a first-day aftermarket spike after pricing an upsized IPO at the top of its proposed range, adding 2.5 million shares on top of its goal and raising $255 million. The company opened 26% above its offering price, and finished Friday’s session up $5 (29%) to $22...