Almost half of all customer enquiries to brokers ended in a mortgage completion in the third quarter of 2015.
One in three customer enquiries failed to progress to application.
The first edition of the Mortgage Market Tracker from the Intermediary Mortgage Lenders Association (IMLA) also showed that almost four out of five brokers are "very confident" about their own business.
Its figures show that 67% of initial borrower enquiries led to an application. Brokers then converted 83% of these applications into offers, and 84% of offers into completions.
The largest percentage of dropouts occurred during the initial stage, when 33% of borrower enquiries failed to lead to an application.
Intermediaries attributed 27% of all dropouts to lender declines, with the remaining 73% due to client or broker withdrawals.
Small firms report the most conversions but they also reported the highest rate of dropouts due to lender declines at 35% compared with an industry average of 27%.
Peter Williams, executive director of IMLA, said the intermediary channel has never been more important to the UK mortgage market.
“Regulatory changes have brought new assessments and criteria to contend with, but this data suggests the majority of applications are getting the green light.
“It also shows that brokers are playing an invaluable role in the earlier stages by assessing borrowers’ circumstances and providing realistic advice and recommendations.”
William said it is encouraging intermediaries are upbeat about the business outlook after a period of fundamental change.
Ray Boulger, senior technical manager at John Charcol, said the success rate for applications is much higher when made through a broker. “This reflects the understanding brokers have of lenders’ criteria, which changes frequently, and the fact that lenders’ affordability calculations vary considerably.”
Should the original lender decline to offer the amount required for any reason, a broker can quickly use the information already available to assess whether an alternative lender could help, Boulger said.