TORONTO, May 24 (Reuters) - Toronto's main stock index fell shortly after the open on Tuesday, weighed by renewed concerns about the euro zone's ongoing debt problems.
Part of the weakness was to catch up with sharp declines in major markets on Monday when Canadian financial markets were closed for a holiday.
The Toronto Stock Exchange's S&P/TSX composite index .GSPTSE was off 36.20 points at 13,616.07, after opening slightly firmer. Nine of 10 main groups were lower. (Reporting by Ka Yan Ng; Editing by Jeffrey Hodgson)