[7] It was formed through the merger of Banca Intesa and Sanpaolo IMI in 2007, but has a corporate identity stretching back to its first foundation as Istituto Bancario San Paolo di Torino in 1583.

The cassa di risparmio was started by an Italian philanthropic group, the Central Committee of Charity; a response by the government to the hard economic times of the early 19th century.

In the early 20th century the bank helped Italian companies in the North obtain capital during and after World Wars 1 and 2, chiefly under the guidance of Giordano Dell'Amore.

[17] The bank increased in size during the 1990s due to numerous acquisitions (Citibank Italia, Banca Vallone di Galatina and European securities dealer Caboto among others).

[18][19][20] Banca Commerciale Italiana (BCI) started in 1894 as a corporate loans lender operating in the commercial industry of Northern Italy.

[32] In 2009, group acquisitions included a 30% interest in business info company MF Honyvem, and an increased stake in Alitalia – Compagnia Aerea Italiana up to 33.3%[33] Even though the bank was rumoured to have been working with the government to keep Air France from acquiring a stake in Alitalia, Air France eventually acquired 25%.

[48] On 17 February 2020, Carlo Messina unexpectedly announced the launch of a voluntary OPS (public exchange offer) for 4.9 billion euro towards UBI Banca which provided for the delivery of 17 Intesa Sanpaolo shares for every 10 UBI Banca shares newly issued with a premium of 27.6% compared to the stock market listing on Friday 14 February.

[49] In addition, on 27 April 2020 Intesa, which has access to three million UBI customers, obtained from the extraordinary shareholders' meeting the approval of a capital increase in support of the takeover bid.

UnipolSai has already reached an agreement to take over the business branches of the insurance companies Banca Assurance Popolari, Lombardia Vita and Aviva Italia, owned by UBI.

The Bolognese insurance group supported the share capital increase of 802.26 million euros of BPER Banca, the Emilian bank of which it is the first shareholder with 19.9%.

In July 2020, the antitrust authority ordered Intesa to sell as many of its own branches, in the event that the public subscription offer does not reach 67% of the shares.

The sale is scheduled for the end of 2020, with the aim of closing the financial statements in April 2021, presenting a credit institution in seventh place in Europe in terms of size, with a value of assets under management of 1.1 trillion, loans for 460 billion and profits for five.

Therefore, having exceeded 90% of the share capital, the delisting procedures have begun which have led Intesa Sanpaolo to become the sole shareholder of UBI Banca.

[58] In August 2024, Intesa Sanpaolo fired one of its clerks, Vincenzo Coviello, after an internal investigation unearthed evidence of illicit activity.

[59] The public prosecutor's office of Bari, Italy, has since accused Coviello of compromising national security by repeatedly gaining unauthorised access to the bank accounts of about 3,500 individuals, including the Italian prime minister Giorgia Meloni, Defence Minister Guido Crosetto, the prosecutor of the National Anti-Mafia and Anti-Terrorism Directorate, and several officers of the Carabinieri and Italy's financial police, Guardia di Finanza.

[6] The Group's activities are divided into six divisions:[5] In addition to its strong presence in Italy, Intesa Sanpaolo has branches and representative offices around the world.