As Swiss officials and UBS Group AG raced to put together a deal for the takeover of Credit Suisse Group Inc., bonds of the embattled lender rose in a rare weekend trading session.

One large dealer was quoting Credit Suisse bonds at levels that were as much as 6.5 points higher than Friday, according to a person with knowledge of the matter, who asked not to be identified discussing private activity in the over-the-counter market.