The national scale rating on Turkey-based reinsurer Milli Reasurans T.A.S. (Milli Re) reflects Standard&Poor's Ratings Services' view of the company's dominant competitive position in Turkey and its good prospective capitalization. The ratings are constrained by the company's marginal quality of investments from a global perspective, its concentration in the Turkish market, which exacerbates the potential effect of exposure to earthquake-modeling risk, and marginal operating performance. While we consider Milli Re strategically important to its parent, Turkiye Is Bankasi AS (Isbank; BB/Stable/B, Turkey national scale rating trAA/--/trA-1), its ratings do not receive any uplift because of those on its parent. We consider the quality of investments to be one of the constraining factors for the rating. Milli Re invests