HONG KONG (Reuters) -HSBC ( HSBC ) launched a $3 billion share buyback after reporting a 25% fall in first-quarter profit on Tuesday due to one time charges related to business disposals in Canada and Argentina.

The London-based bank reported profit before tax of $9.5 billion in the first quarter. That compared with $12.7 billion a year earlier and $7.8 billion average of analyst estimates compiled by the bank.

"The macroeconomic environment is facing heightened uncertainty, in particular from protectionist trade policies, creating volatility in both economic forecasts and financial markets and adversely impacting consumer and business sentiment," the bank said in its earnings release.