Several leading US national securities law firms are looking into the proposed merger of Duff & Phelps, which handled the football club's insolvency, with The Carlyle Group in a deal subject to shareholder approval.
Shares in Duff & Phelps leapt in value after the deal was announced, but it has hit trouble because some shareholders say they are being shortchanged.
New York-based Tripp Levy, which says it is representing Duff & Phelps shareholders in connection with the private equity buyout, says that, while the agreement values the company at $15.55 (£9.50) per share, analysts have projected the inherent value of the company is at least $24 (£14.80) per share.
While such challenges are not uncommon, the potential for a lucrative law suit has attracted a host of legal firms who are circling the deal.
According to one analyst, there are concerns members of senior management will take part in the buying side of the deal, rolling their shares and other options into a new firm acting as buyer.
While not unusual, this is viewed as a potential conflict of interest. Although they work for the shareholders in Duff & Phelps, they also have an interest as investors in the buyer in ensuring the best possible deal.
Tripp Levy said: "The investigation concerns, among other things, whether the con-sideration to be paid to Duff shareholders is unfair, inadequate, and substantially below the fair or inherent value of Duff.
"The investigation further concerns whether the board of directors of Duff, including its senior management who are participating in the buyout of the company's equity, may have breached their fiduciary duties by not acting in shareholders' best interests in connection with the sale process of Duff."
Dallas-based former US Securities and Exchange Commission attorney Willie Briscoe and a partner in securities law firm Powers Taylor, also based in Texas, is pursuing Duff & Phelps on behalf of shareholders.
Mr Briscoe said: "Due to the proposed sale price, the size of the deal and other factors, we believe this transaction may undervalue Duff's stock. Our lawsuit will seek to obtain the highest share price for all shareholders."
Jim Baker, lead analyst for Johnson & Weaver, which is also examining the buyout, said: "The investor group's offer appears to be lower than I would expect based on market valuation."
Pennsylvania-based Ryan & Maniskas and New York-based firms Faruqi & Faruqi and Levi & Korsinski have also moved to look into the deal.
It is unclear whether Paul Clark and David Whitehouse, the former Ibrox administrators and managing directors of the firm in London and Manchester, will share in any windfall from the deal.
Noah Gottdiener, chief executive officer of Duff & Phelps, said its legal and financial advisers agree the transaction "is in the best interest of our stockholders, who will receive an immediate and certain cash premium for their shares".
All members of the senior management team have agreed to remain in their posts after the merger.
The firm, which has offices worldwide, was brought in by former Rangers owner Craig Whyte in February last year after the club was placed into administration over an unpaid £9m tax and PAYE bill.
Duff and Phelps earned £2.7m from the process, but was unable to find a buyer and Rangers were placed into liquidation.