Movant sought leave to file an untimely proof of claim in debtors' chapter 11 bankruptcies, asserting it was unaware of its potential claim until discovery had been conducted in a different district court action. The court held that Bankruptcy Rules 3003(c)(3) and 9006(b)(1) require a showing of "cause" for extensions of time and, even then, such relief was in the court's discretion. As the extension request was made after expiration of the claims bar, the court ruled that it could only use its discretion to grant the relief if the failure to meet the deadline resulted from "excusable neglect." Given the procedural posture of the case, allowing a new claim would require reworking of the proposed plan and a new disclosure statement. In addition, movant failed to show a probability of success of its claim in debtors' bankruptcy. The court concluded that, even if excusable neglect had been established, it would be inappropriate to exercise its discretion to allow the filing of a late claim.