Residential property owner Grainger swung back into a pre-tax profit and said it will pay an interim dividend but warned its expects the economic environment to remain challenging. Commenting on trading conditions, chairman Robin Broadhurst said, "Although we anticipate that general economic conditions will continue to be challenging for some time, our resilient, cash generative portfolio will stand us in good stead." Profit before tax improved to £3.5m for the six months ended 31 March 2010 from a loss of £143.0m the year before. Gross NAV per share fell to 191p from 194p at 30 Sept 2009. Completed residential sales rose to £79m from £55m the year before with margins on sales of vacant properties improving to 42% from 37% in 2009.Broadhurst added that prospects for the group are good. "Our immediate focus is to take advantage of buying opportunities in our core reversionary portfolios and to leverage our residential skills and experience to explore value accretive and well-priced opportunities on behalf of our shareholders, investors and partners."Grainger said it will pay an interim dividend of 0.5p per share. No payment was made last year.