The shares, which were above 6p in February but at 3.5p before the talks with Baker Tilly were unveiled on July 25, crashed to 0.85p with more than 15 million changing hands.
Shares in RSM Tenon were trading at more than 66p as recently as January 2011
Yesterday, RSM Tenon said that the discussions with Baker Tilly were continuing.
It went on: "It is now likely that, as a consequence of the company's high debt level, if an offer is made by Baker Tilly, minimal value, if any, will be attributed to the issued share capital of the company."
Lloyds owns 10% of the shares but holds the company's £90m of debt. In February Tenon said it had entered into discussions with Lloyds to avert the "significant risk of a facility breach" over the next 12 months, since when it has stressed Lloyds' support for the group as a going concern.
RSM Tenon said: "Lloyds Banking Group continues to be supportive of the business as the company discusses with it ways to address its high level of borrowings."
Baker Tilly has until next Thursday to declare its intentions.
RSM Tenon added: "This announcement is being made with the agreement and approval of Baker Tilly.
"This announcement does not amount to a firm intention to make an offer and, accordingly, there can be no certainty that an offer will be made."