(215 ILCS 5/155.25a) (from Ch. 73, par. 767.25a)
    Sec. 155.25a. Notwithstanding the provisions of subsection (D) of Section 123B-9, a purchasing group may purchase insurance providing for a group aggregate limit from an insurer licensed to write medical liability insurance in this State if (1) such group is domiciled in Illinois and all or substantially all of such group's members are residents of Illinois, (2) each insured in the purchasing group is specifically informed prior to issuance of the policy to such insured of the existence of the group aggregate limit, and (3) either (a) the amount of the group aggregate limit is determined by the Director in his discretion to be sufficiently high (when considered in conjunction with other factors such as each individual insured's per claim limit and each individual insured's aggregate limit), such that the risk that the group aggregate limit will be exhausted is not substantial, or (b) (i) each individual insured's aggregate limit is not more than 300% of such individual insured's per claim limit and (ii) the group aggregate limit (at the time of the insured's claim) is equal to or exceeds the amount set forth in the following table:
Number of InsuredsRequired Purchasing
in PurchasingGroup Aggregate Limit
Group
Less than 10Individual claim limit X
Number of Insureds
10 to 24The sum of (i) 3 X the
individual claim limit,
plus (ii) the individual
claim limit X the Number
of Insureds X 2/3
25 to 50The sum of (i) 7 X the
individual claim
limit, plus (ii) the individual
claim limit X the Number of
Insureds X 1/2
Over 50The sum of (i) 17 X the individual
claim limit, plus (ii) the
individual claim limit X the
Number of Insureds X 3/10.
(Source: P.A. 86-632.)