Shares of Emulex Corp. sank Monday after an analyst downgraded the Costa Mesa networking electronics maker.

Investors sent shares down 9.6% in afternoon trading to a market value of about $588 million after San Francisco-based investment bank ThinkEquity LLC downgraded the company to “hold” from “buy” and cut its price target to $8 from $12.

Emulex designs and makes networking equipment that connects storage, servers and data centers. It is among a burgeoning group of networking-equipment makers competing in the emerging 10-gigabit Ethernet connection market for data centers.

Such technology is seen as an improvement over fibre-channel and 1-gigabit connections, which are prevalent in data centers today.

For years the company has battled Aliso Viejo-based rival QLogic Corp., the market share leader in fibre-channel adapters and another 10-gigabit player.

Emulex spun off QLogic in the early 1990s.