LONDON - HSBC is to wind down its M&A and equities businesses in Europe, Britain and the Americas, a staff memo showed on Tuesday, signalling its biggest retrenchment from investment banking in decades and an acceleration of its shift to Asia.

"Our intention is to move to a more competitive, scalable, financing-led model," Michael Roberts, CEO HSBC Bank said in the memo seen by Reuters, which said the lender would retain more focused M&A and Equity Capital Markets (ECM) capabilities in Asia and the Middle East.

CEO Georges Elhedery is leading a major cost-cutting exercise at Europe's largest bank launched after he took the top job in September.

The sweeping overhaul is aimed at streamlining costs and improving accountability of performance, as well as a renewed focus on Asia, where it earns the bulk of its profit.

Analysts at that time questioned the scale of savings Elhedery could achieve and which parts of the bank would be affected, given the years of restructuring his predecessors had attempted and the bank's steadfast ambition to remain a global, full-service bank.

HSBC will keep its debt capital markets and leveraged acquisition finance operations globally, Roberts told staff in the memo, which acknowledged how "unsettling" the news would be for bankers who advise on dealmaking and corporate equity raising, such as through initial public offerings.

It was unclear precisely how many roles would be cut, or the likely savings, or how many bankers might be redeployed to other financing businesses where HSBC considers it is better able to compete with U.S. rivals.

"I've lost count of the number of times HSBC has been in and out of ECM in the UK. It never seems to succeed," Shore Capital analyst Gary Greenwood told Reuters.

"At the end of the day, these are expensive businesses to run and if you are not winning the business and generating the fees then it's easy to lose money."

HSBC shares were little changed after the news, down by 0.7% at 819 pence by 1004 GMT, valuing the bank at about 147 billion pounds ($182.9 billion).

Some commentators described the timing of HSBC's decision as surprising, given capital markets activity is expected to grow in the near term, fuelled by expectations of interest rate cuts and pro-growth policymaking across the West, in the wake of U.S. President Donald Trump's return to power.

"The bank is being run with medium to long-term view," RBC Capital Markets analyst Ben Toms told Reuters.

"Geographically, the move reflects the continued shift from West to East, where growth and profitability are higher."

HSBC's decision to shutter the businesses was earlier reported by Bloomberg.

($1 = 0.8037 pounds)

(Reporting by Sinead Cruise; Editing by Tommy Reggiori Wilkes, Elisa Martinuzzi and Louise Heavens)