Three of the major banks lost ground in the household deposits market in February, with Westpac suffering net outflow of more than A$300 million on retail accounts.However, official monthly data published by APRA, shows an even bigger outflow from business and corporate account holders, who - in net terms - called in $3.5 billion from Westpac's vaults.Solid growth in government business and certificates of deposit softened the impact on Westpac's total deposit base, which fell to $447.6 billion at the end of February from $450.8 billion a month before.The poor result is difficult to fathom, given that Westpac has outpaced deposit growth of the other major banks over the last two years and its pricing of term products is in line with, or better than, its peers.While Commonwealth Bank entered the New Year mired in controversy, the APRA data indicates it has resumed winning customers.CBA boosted its retail deposits by more than $670 million to $251.8 billion in February and enjoyed reasonable growth across most segments of the deposit market.ANZ is continuing to make inroads into the business deposits market after managing to add more than $1.4 billion from corporate and SME customers.However, total deposits held on behalf of personal account holders rose by only $1 million.NAB had a disappointing month, ceding market share in both the retail and business deposits markets.The bank increased retail deposits by only $13 million to $125.5 billion and suffered a $1 billion net outflow of cash on accounts held by corporates and SME customers.NAB's total deposit base fell $1.4 billion to $360.9 billion.The national retail deposits segment expanded by $1.52 billion during the short month, with regional and mutual banks collecting the lion's share of the growth.Except for CBA, the major banks lost market share of the household segment to four regional banks: ING Direct (up $240 million), ME Bank (up $120 million), AMP Bank (up $34 million) and Suncorp (up $40 million).However, the big winner of the month in terms of market share improvement was Beyond Bank, which grew its personal deposits by $184 million to $4.1 billion. This equates to a remarkable 4.69 per cent rise in the bank's deposit base during the month but is likely to have included the migration of more than $170 million in deposits from the balance sheet of merger partner, My Credit Union.Several prominent small banks - Bendigo and Bank of Queensland - appear to be struggling to hold on to deposit customers.Bendigo's retail deposits declined by $66 million, while BoQ shed more than $200 million.