Cisco, Harmonic shares slide on weak margin outlook; Accelerant jumps

Cisco Systems Inc. shares fell more than 2% in premarket trading on Tuesday after the networking giant signaled pressure on margins, citing higher component costs and competitive pricing. The company’s outlook, delivered alongside its quarterly results, suggests margins may remain under pressure in the near term despite steady revenue growth.

Harmonic Inc., a video infrastructure provider, also slid premarket after lowering its full-year margin guidance, attributing the revision to slower-than-expected demand and elevated operating expenses. The company’s stock was down roughly 3% ahead of the market open.

In contrast, Accelerant Pharmaceuticals Inc. surged more than 15% premarket after announcing a $100 million share repurchase program. The biopharmaceutical firm’s move to return capital to shareholders followed its strong second-quarter revenue and earnings beat, which exceeded analyst expectations.

Analysts noted the contrasting performances reflected differing sector dynamics, with technology and infrastructure firms facing margin headwinds while biotech companies benefited from strong product demand and buyback activity.