Commonwealth Bank's otherwise strong performance in the 2009/10 financial year was coloured by losses in market share across a number of businesses. The bank lost share in home loans, retail deposits, business lending, business deposits and equity trading.It also lost share in New Zealand home loans, retail deposits, business lending and funds under management.Commonwealth's chief executive, Ralph Norris, said the bank was interested in profitable growth and would not chase share for its own sake. He said a highlight was the depth of customer relationships, with 2.64 products per customer. The bank claims the greatest depth of customer relationships among its big bank peers. The more products the customer has the more profitable the relationship.Norris said that over the past five years the bank had picked up significant market share and the performance of the past year had to be seen in that context.In the Australian retail bank, which is the group's biggest division (contributing more than 40 per cent of earnings), the drop in share was due, in part, to Commonwealth's decision to put home loan interest rates up by 45 basis points last November (20 basis points higher than the change in the official cash rate).Customer satisfaction fell away sharply after that move and the bank has had to resort to some deep discounting of its standard variable rate to maintain sales momentum.Norris said: "It was the right decision. If I had to make it again I would. If I am going to be criticised for running a bank prudently, I am guilty as charged."Norris said that the situation in the group's other big division, business and private banking, was better than it first appeared. A lot of the lost share came from a decision to exit "dog-eared" exposures that came with the acquisition of Bankwest. Small business and middle-market lending share has grown.Ross McEwan, head of CBA's retail bank, also pointed out that the bank's growth rate in key products was approaching system once again."To me, you're smarter growing at a time when the margins are thicker, and then holding onto those customers when the margins are thinner.  "So I've been happy to run just under system and hold on to our margin over the last 12 months, but we have been building back up from about two basis points off system in the last month and our margins have been maintained."