Picture Newswire/ Gaye Gerard. Australian materials stocks have surged as an AI trade proxy, helping the ASX 200 close higher for a fourth consecutive month. Picture NewsWire / Gaye Gerard. On a mixed day of trading, strong gains in materials were offset by falls in healthcare and consumer staple stocks. Picture: Newswire / Gaye GerardIt was also a weak day of trading for consumer staples stocks, as the major supermarkets traded in the red.