MADRID/BARCELONA (Reuters) -Shares in Grifols fell by 30% on Tuesday, wiping nearly $3 billion off its market value, after hedge fund Gotham City Research questioned its accounting, prompting the Spanish drugmaker to "categorically" deny any wrongdoing. Gotham questioned Grifols' reported debt and earnings before interest, taxes, depreciation and amortisation (EBITDA), and leverage ratio of 6.7 times. It said the leverage ratio is close to 10 to 13 times EBITDA.