The Globe and Mail reports in its Wednesday edition that mortgage shoppers should know that the interest rate you ultimately get depends heavily on who you speak with and how well you negotiate. The Globe's guest columnist Hanif Bayat writes that two borrowers with identical financial profiles can walk away with quite different rates. Which means that understanding how lenders price mortgages can save you thousands. The Big Six banks control more than 70 per cent of the residential mortgage market, yet they rarely reveal the lowest rates they offer prime borrowers. Their advertised rates are much higher than what clients actually receive. This opacity is intentional: Disclosing true floor rates would limit price differentiation between customers and eat into the banks' profit. Because most Canadians default to the Big Six because of each bank's brand and branch network, there is little pressure for greater transparency. Data from WOWA Data Labs show a significant gap between advertised mortgage rates and the actual rates borrowers receive. For three-year fixed conventional mortgages, RBC, TD, Scotiabank, BMO and CIBC, on average, offered rates more than 0.50 percentage points below their advertised rates.