Shares in Nintendo jumped 14% on Tuesday as the soaring popularity of its Pokemon Go smartphone app showed no sign of abating.
The computer games giant's share price closed at 31,700 yen (£226.69), meaning its market value has now more than doubled to 4.5 trillion yen (£32 billion) since it was launched in America on July 6.
It comes after the Japanese company recorded its biggest gain since revealing the Nintendo Entertainment System (NES) in 1983 when shares closed up 24.5% at 20,260 Japanese yen (£152.28) on July 11.
Neil Wilson, markets analyst at ETX Capital, warned that the firm could be entering "bubble territory" and its rally may start to falter soon.
He said: "The increase in the firm's market capitalisation - which has doubled to 42 billion US dollars - means it's bigger than Hermes, Sony, Yahoo and Glencore.
"But we're in bubble territory now - the stock's vertiginous rally may not last. What goes up this fast usually comes down with a bump.
"Pokemon Go is a game-changer for Nintendo - a clear sign that it's embraced the smartphone gaming revolution."
But he added: "To old City hacks, the share's bounce looks a little overdone and it's broken so far clear of any support levels that a fall could be nasty for those who bought into the rally."
Pokemon Go is Nintendo's first foray into the mobile gaming market and has emerged as a global craze with players hooked to their handsets since it launched in the US, Australia and New Zealand.
The game is now available in 35 countries and was released in the UK on July 14.
In the augmented reality game developed by Niantic and The Pokemon Company, players travel around the real world to capture and train creatures known as Pokemon - the most famous of which is Pikachu.
However, its release has triggered warnings from the NSPCC and police in London amid fears that it could be putting the safety of gamers - including children - at risk.
The app is free, making money by asking gamers to buy additional content once they have started playing.
Nintendo is best known for its gaming franchise Super Mario Brothers and its console the Wii U, which it launched in America in November 2012.