Business-to-business software maker

PurchasePro

(PPRO)

was down 15.4% at midday after

Prudential Securities

downgraded it to accumulate from strong buy.

The reason cited was lower-than-expected rates of adoption, but the downgrade is also reportedly based on news that a federal prisoner is suing PurchasePro, accusing the company of stealing his ideas.

Prudential said the suit appears to be frivolous but it could hurt investors' perceptions of the company.