Australian business sentiment improved sharply in June, according to National Australia Bank’s monthly survey released on Tuesday. The Business Confidence Index rose to 5, up from 2 in May, while the Business Conditions Index jumped to 9 from 0. Readings above zero indicate net optimism among respondents. NAB did not publish consensus forecasts for the series. The rebound suggests firms are seeing a firmer operating environment despite higher borrowing costs and soft consumer spending. NAB said trading, profitability and employment sub-indexes all contributed to the stronger conditions reading.