ANZ wrote 170,315 home loans over its financial year to September 2018, a document recently released on the website of the banking royal commission shows.Shayne Elliott, ANZ's managing director, wrote to the commissioner, Kenneth Hayne, on December 7 last year "to bring additional information and data to your attention" on a number of topics. This was a week or so after his evidence in late November. Part of this letter considers the vexed topic - at least to mortgage brokers - on how they are paid and whether customers might be directly charged.Elliott's letter supplies a rare glimpse of precise data from a major lender on its new business volumes, and may add to questions over the bank's positioning in the mortgage market amid the "credit crunch". ANZ's market share in mortgages declined by 30 basis points over calendar 2018 to around 15.95 per cent late last year, giving up hard won gains in market share dating from early 2017. (APRA will release its latest data on the mortgage market and broader banking statistics today.)The ANZ CEO includes a table on the number of loans sold through the bank's proprietary channel (87,425) and the number sold through the broker channel (82,890). ANZ thus originates 51.3 per cent of all home loans via its own networks, though 15 per cent of all loans were "top-up mortgages arranged by ANZ lenders", suggesting the broker channel is the source of the bulk of ANZ's "new" home loan flows.The bank disclosed data across five tiers (based on loan value) and it's clear the broker channel accounts for the most valuable mortgage business for ANZ, from the middle market to seven figure loans.