A partnership will not be considered readily tradable if the sum of the percentage interests in partnership capital or profits transferred during the tax year of the partnership (other than private transfers and transfers through qualifying redemption and repurchase agreements or through matching services,) does not exceed 2 percent of the total interests in partnership capital or profits. Total interests in partnership capital or profits are determined by reference to all outstanding interests in the partnership. However, if the general partner and any related entities own more than 10 percent of the interests, their interests will not be counted. For transfers other than block transfers, the percentages transferred are determined monthly, so that the percentage interests transferred during the tax year is the sum of the percentage interests transferred each month.
Treas. Reg. §1.7704-1(j)-(k)