* Former Goldman Sachs banker joined Feb. 2016
* Westerman cut jobs, cracked down on underperformers
* Rare external hire for such a senior role (Adds background, quote)
By Lawrence White
LONDON, Nov 23 (Reuters) - One of HSBC's most senior investment bankers, Matthew Westerman, is leaving the firm immediately, according to an internal memo seen by Reuters.
Westerman, co-head of global banking at HSBC, joined the lender just under two years ago from Goldman Sachs with a mandate to shake up the division and improve performance.
A rare external hire for such a senior role at HSBC, Westerman made sweeping changes after his arrival in February 2016 including cutting dozens of senior bankers and cracking down on staff who did not spend enough time meeting clients.
British-born Westerman, seen at one time by some inside the HSBC as a future candidate to run the whole bank, ruffled feathers internally with the number of job cuts he made, sources at HSBC said last year.
Westerman was hired directly by HSBC Chief Executive Stuart Gulliver and was familiar with the European bank from his time covering it as a senior investment banker at Goldman Sachs.
No reason was given in the HSBC memo for his departure less than two years into the role.
"He and Robin Phillips have together driven improved financial and market share performance and reinvigorated our approach to collaboration in Global Banking and Markets," the head of that division, Samir Assaf, said in the memo.
Westerman's co-head Robin Phillips will manage the global banking unit following his departure, the memo said.
An HSBC spokeswoman confirmed the contents of the memo. (Editing by Jason Neely, Greg Mahlich)