Premise: TORONTO, April 23 Canada's main stock index turned negative during a sharp slip in the last half hour of trade on Wednesday. The Toronto Stock Exchange's S&P/TSX composite index shed around 20 points in minutes, pushing it more than 8 points below its last close, to 14,547.56. Six of the 10 main groups were in negative territory. (Reporting by Alastair Sharp; Editing by Meredith Mazzilli)
Hypothesis: More than half of the 10 main groups were in the negative territory.