TD CanadaTrust 6 month convertible mortgage
http://www.tdcanadatrust.com/mortgages/sixmonth.jsp
“If you like to take advantage of interest rate fluctuations, our competitive Six-Month Convertible Mortgage is for you. This mortgage lets you benefit from the typically lower interest rate of a six-month mortgage, with the option of converting to a longer closed term at any time during the six months — at no cost to you.”