Definition of 'Halloween Massacre'
Canada's decision to tax all income trusts domiciled in Canada. In October 2006, Canada's minister of finance, Jim Flaherty, announced that all income trusts would be taxed in a similar manner as corporations at a rate over 30% on taxable income, causing unit holders' values to decrease dramatically virtually overnight.
Investopedia explains 'Halloween Massacre'
Income trusts, which were permitted to make distributions to unit holders on a pretax basis under old Canadian income tax laws, were a popular investment vehicle in the early 2000s, especially in Canada. The Canadian energy sector was hardest hit by the change, and suffered an estimated loss of about $35 billion to investors, giving rise to the term "massacre".
This change in the Canadian tax law, which was largely debated after the fact, was made to remedy a perceived loss of tax revenue.