What would you do if a used-car salesman told you it's against the lawto check the odometer before buying? You'd shake your head and walkstraight out. Similarly, investors stalked out of AmeriCredit ( ACF) stock Wednesday after the auto lender failed to offer important data in its fiscal fourth-quarterearnings statement. Improbably in this disclosure-obsessed era, the companyclaimed it wouldn't share the information because of regulatory guidance. The most notable omission was AmeriCredit's figure for the effectivesize of its bad loan reserve. The reserve number is critical for investorsattempting to gauge the amount of financial cushion a lender has againstbad loans. It's especially important when the lender, like AmeriCredit, isexperiencing a sharp rise in problem loans. The omission could imply that AmeriCredit, which targets borrowers withtainted or incomplete credit histories, has failed to sufficiently reserveagainst bad loans. Meanwhile, cash continued to circle the drain in thelatest quarter and credit quality deteriorated, pointing toward a possiblesqueeze on the company's liquidity. AmeriCredit's already-battered stocklost a quarter of its value Wednesday, falling $4.05 to $12, a 52-week low.