Credit growth in Australia turned negative during December 2008, and for the first time since 1992 and the tail of the early 1990s economic downturn according to credit aggregates published by the Reserve Bank of Australia on Friday. A decline of 1.1 per cent in the volatile business lending series was the main driver of the fall. Separate APRA data on bank lending suggests that a decline in the aggregate level of loans from foreign banks may explain most of this fall.Whether this is a supply problem and to what extent this reflects demand as all businesses respond to the bleak outlook for growth in sales, is something not clarified by the data.A similar decline of 1.1 per cent in the personal lending series drove the rest of the fall and is easier to explain. The level of margin lending continues to decline in line with the equities market, while presumably many households paid down credit card debt in December (and despite Christmas spending patterns) with the help of one-off family payments from Centrelink.Some other long-running themes are also evident in the RBA and APRA data, and mainly the steady improvement of the market share of the big four banks.In residential lending the big four increased their level of home lending by about $21 billion over the December 2008 quarter, compared with growth for the whole sector (banks and non-banks) of only $13 billion.