Wednesday's release of March existing homes sales data should show improvement over dismal results in February, but the housing market overall is underperforming, according to one expert. First American Financial (FAF) - Get Free Report , a leading provider of real estate title insurance, tracks housing sales using its proprietary Potential Home Sales Model. The model provides a measurement on whether home sales are performing at their long-term potential level. Right now, the market is not. 'We see very, very tight inventories and falls in confidence amongst consumers,' said Mark Fleming, Chief Economist at First American Financial.