US President Donald Trump gave a 15 September deadline for the Chinese-owned app to sell or shut down.
The Trump administration claims TikTok and other Chinese apps are national security threats.
Microsoft and Oracle led the race to buy TikTok from Chinese firm ByteDance.
The Wall Street Journal and Reuters have reported that Oracle, which sells database technology and cloud systems to businesses, had won the bidding war, citing people familiar with the matter.
Earlier reports had said Oracle was seriously considering buying TikTok's businesses in the US, Canada, Australia and New Zealand with investment firms, including General Atlantic and Sequoia Capital.
A TikTok spokesperson told the BBC the firm was "not commenting on either the Microsoft development nor the Oracle speculation".