https://www.reuters.com/article/us-bitcoin-intesasanpaolo/intesa-ceo-warns-of-bitcoin-bubble-urges-global-regulation-tv-idUSKBN1DV5SL >The head of Italy's top retail bank Intesa Sanpaolo joined a growing chorus of Bitcoin critics, calling the wild gyrations in the price of the cryptocurrency a speculative bubble and saying global regulatory scrutiny was essential.