Fitbit Inc. shares surged as much as 42% in Monday trading after Reuters reported that Alphabet Inc. /zigman2/quotes/202490156/composite GOOGL +0.72% /zigman2/quotes/205453964/composite GOOG +0.94% has made a buyout offer to the wearables maker. The report , which cited anonymous sources, didn't discuss the offer price and maintained that a final deal may not happen. Fitbit shares have languished in recent years amid competition from Apple Inc.'s /zigman2/quotes/202934861/composite AAPL +0.17% Apple Watch. Most recently, Fitbit has been trying to branch into the healthcare ecosystem by getting health plans to incorporate Fitbit devices into their offerings. Fitbit shares are off some 70% from their initial-public-offering price of $20. With Monday's rally, the stock is up 11% on the year, while the S&P 500 /zigman2/quotes/210599714/realtime SPX -0.15% has gained 21%.