SAN FRANCISCO (AP) — Billionaire Warren Buffett has established his credentials as a savvy money manager, but Internet trailblazer Marc Andreessen doubts the stock market sage knows much about financial innovations such as the virtual currency bitcoin.

The wild swings in bitcoin’s value during recent months prompted Buffett, 83, to dismiss the currency as a “mirage” during an interview on the financial news channel CNBC earlier this month.