(Reuters) - UniCredit has approached Commerzbank about exploring merger talks, a source with knowledge of the matter said, after the Italian lender bought 9% of the German bank.

Commerzbank has, like some other banks, had a rocky history with big mergers and acquisitions over the years.

These are some of the key moments:

1870-1970s

The bank was founded in Hamburg and later moved to Berlin. It relocated to Frankfurt in 1970 as one of Germany's leading banks, focusing on retail customers and corporate firms.

1970s

Expands to London and New York, and other European capitals.

2008

Commerzbank agrees to buy Dresdner Bank, one of Germany's top banks, from insurer Allianz in a $14.5 billion deal.

Commerzbank is Germany's first commercial bank to turn to the government for capital during the global financial crisis.

2009

In a bailout, Germany takes a stake of 25% plus one share in Commerzbank in return for an additional 10 billion euro capital injection.

2011-2013

European debt crisis continues.

2016

Commerzbank embarks on a multi-year restructuring.

2017

U.S. investor Cerberus builds a stake controlling 5% of the German bank's voting rights.

UniCredit told Berlin it is interested in eventually merging with Commerzbank, Reuters reported, citing people familiar with the matter, a combination that would create one of Europe's biggest banks.

BNP Paribas' then Chairman Jean Lemierre dampened rumours that it was is interested in a tie-up with Commerzbank.

2018

Commerzbank is expelled from the blue-chip DAX index.

Deutsche Bank dismissed as "fictions" media reports suggesting that Germany's biggest bank might seek tie-ups with Switzerland's UBS or Commerzbank.

2019

Cerberus is open to a merger between Germany's two biggest lenders.

Deutsche Bank and Commerzbank hold merger talks, but call them off weeks later.

UniCredit engaged investment bankers to advise it on a potential bid for Commerzbank.

Commerzbank's supervisory board approved plans to cut thousands of staff and close a fifth of its branches after the failed merger with Deutsche Bank.

2020

In a u-turn, Commerzbank said that it would not sell its Polish subsidiary mBank, citing poor market conditions.

Cerberus calls on Commerzbank to appoint two of its nominees to the supervisory board, cut costs and adopt a new strategy.

Commerzbank's chairman and chief executive step down, bowing to demands from Cerberus.

2021

Commerzbank's new CEO, Manfred Knof, wants to cut 10,000 jobs and close hundreds of branches as part of a strategy revamp announced just weeks after taking on the top job.

Knof says Commerzbank is working to remain independent.

2022-2023

UniCredit CEO Andrea Orcel previously approached Knof about a potential deal in early 2022, before the Ukraine war, people with knowledge of the matter have told Reuters.

Commerzbank returns to profit and rejoins the DAX.

2024

Jan. 23 Knof played down prospects of a possible merger with Deutsche Bank, saying such a tie-up was not under discussion at his bank and he was striving to keep the bank independent.

May 15 Commerzbank wants to "tone down" merger speculation and is entirely focused on its current strategy, which is the "best prerequisite" for to stay independent, Knof said.

Sept. 3 Germany intends to reduce its 16.5% stake as Commerzbank is stable again years after its rescue, the government said.

Sept. 10 Commerzbank said Knof won't seek another term when his contract ends in December 2025, as the German government began to sell some of its shares.

Sept. 11 UniCredit approached Commerzbank about exploring merger talks, a source with knowledge of the matter said, after Italy's second-largest bank bought a 9% stake.