Donald Trump’s Tax Numbers Sharpen Focus on Treatment of Losses

The weekend revelation of some of Donald Trump’s tax records put the New York real-estate developer on the defensive by showing the extent of his 1990s financial troubles and suggesting those setbacks could have eliminated his federal income-tax bill for years afterward.

Parts of Mr. Trump’s state tax documents from 1995, published over the weekend by the New York Times , show that the Republican presidential nominee reported a $916 million loss on that year’s tax return. That would allow him to legally soak up years of...