$9 billion insurer XL Group ( XL) is a leader in the property-casualty insurance and reinsurance business, providing wholesale insurance products for commercial and industrial customers as well as for other insurers. The firm has historically been one of the most innovative names in risk management products, helping firms to reduce the chances of getting wiped out by a catastrophe. While the insurance industry has become extremely commoditized in recent years, there are still some advantages that come from scale -- and XL has scale. That gives XL the ability to underwrite big, hugely unlikely risks for large corporations that smaller insurance firms don't have the balance sheet to absorb. New products are another big de-equalizer for XL's insurance book; as the firm continues to offer new, innovative financial protection products, firms demanding those offerings have no choice but to pay what XL's underwriting arm wants to charge them. Like other insurance firms, XL took a substantial hit following the financial crisis of 2008. But also like peers, XL has made leaps and bounds to re-solidify its investment portfolio. Now, XL Group's 22.8% ascent in 2013 doesn't look like it's coming to an end any time soon.