A federal judge questioned Qualcomm Inc. Thursday about its failure to share tens of thousands of documents with rival chipmaker Broadcom Corp. in a patent-infringement lawsuit that it lost.

U.S. Magistrate Judge Barbara Major made no decision after a six-hour hearing but said she was struggling to understand how Qualcomm overlooked so many documents and why it didn’t turn them over sooner. A Qualcomm attorney called it an unfortunate but innocent lapse.