A U.S. appeals court found memory chip designer Rambus Inc wrongly destroyed documents related to patent lawsuits it filed, sending its shares down sharply.

The U.S. Court of Appeals for the Federal Circuit said on Friday it was clear that Rambus had destroyed documents but it was not clear that the destruction was so serious that a lower court should have tossed out one of its lawsuits.

It sent the dismissal back to the U.S. District Court in Delaware, adding that the lower court might still decide the shredding was serious enough to cause Rambus to lose the case it brought against Micron Technology, the top U.S. maker of memory chips for computers.

In a related ruling, the appeals court found Rambus destroyed documents related to a patent infringement suit it successfully brought against Korea's Hynix Semiconductor. It asked a California court in that case to review its ruling in view of the document destruction.

The decisions slammed Rambus' shares, which ended Friday down 17.9 percent on Nasdaq.

Rambus designs memory chips and licenses technology used in them to other chipmakers.

Investors had been watching for Friday's appeals court decisions. If the court had ruled for Rambus it would have helped it negotiate additional licensing arrangements.

Much of Rambus' income has come from patent litigation against companies it accuses of not paying for its technology.

We are very disappointed with the decisions in these cases, said Thomas Lavelle, senior vice president and general counsel at Rambus. We are hopeful when the district courts reconsider these decisions, they will find, as we believe, there was no bad faith and no prejudice.

The ruling was more mixed than the drop in the share price would indicate, said Jeff Schreiner, an analyst with Capstone Investments.

What people are missing here, is this did not derail Rambus' patents, so Micron and Hynix are not safe. They were never able to find a silver bullet to stop Rambus, said Schreiner.

Another analyst said the share price drop was over the Hynix lawsuit.

I think the market is reacting to the technical finding of (document) spoliation and the near-term loss of the roughly $400 million that was waiting for it in the Hynix case, said Michael Cohen, principal of MDC Financial Research, LLC, who owns Rambus stock.


The appeals court said it was not clear error for the Delaware court to conclude that Rambus' document policy was aimed at boosting its litigation strategy by frustrating the fact-finding efforts of opponents.

It is undisputed that Rambus destroyed between 9,000 and 18,000 pounds of documents in 300 boxes, the court said in the ruling in the Micron case.

In the Hynix case, the court spoke of 700 boxes of paper shredded on two different Shred Days, adding that Rambus admitted that some destroyed documents were related to contract and licensing negotiations, patent prosecution and Rambus finances.

Hynix and Micron accused Rambus of holding these shredding parties even as the company laid plans to sue them for patent infringement. The lower courts were divided on the issue.

Micron had won in the Delaware court when a judge invalidated 12 Rambus patents, citing document destruction by Rambus as the reason.

But Rambus won against Hynix in a separate trial, when a federal judge in California found that nine Rambus patents were valid and had been infringed.

Trading in Rambus was halted six times on Friday as the stock hit circuit breakers after rapidly rising and then falling through the 10 percent threshold in a matter of minutes.

At nearly 15 million shares traded, volume was 18 times the daily average.

Messages left at Micron and Hynix offices were not returned.

Rambus has filed lawsuits against a long list of technology companies in the past decade. Samsung Electronics settled an infringement lawsuit with Rambus in January 2010 in a deal that could cost it $900 million.

Friday's cases were: Hynix Semiconductor v. Rambus, 09-1299 and Micron Technology v. Rambus 09-1263 in the U.S. Court of Appeals for the Federal Circuit.

(Reporting by Diane Bartz and Noel Randewich; Editing by Tim Dobbyn)