PROSPECTUS SUPPLEMENT SUMMARY The summary contains basic information about us, the debentures and this offering. Because this is a summary, it does not contain all the information you should consider before investing in the debentures. You should carefully read this summary together with the more detailed infornunion, financial statements and notes to the financial statements contained elsewhere or incorporated by reference into this prospectus supplement or the accompanying prospectus. To fully understand this offering, you should read all of these documents. To the extent there is a conflict between the information contained in this prospectus supplement, on the one hand, and the information contained in the accompanying prospectus, on the other hand, the information in this prospectus supplement shall control. Unless otherwise indicated or the context otherwise requires, all references in this prospectus supplement and the accompanying prospectus to "W. R. Berkley." we. " "as. "our" or similar terms refer to W. R. Berkley Corporation. W. R. Berkley Corporation Introduction We are an insurance holding company that is among the largest commercial lines writers in the United States. We operate in the following segments of the property casualty insurance business: • insurance- primarily commercial insurance business, including excess and surplus lines and admitted lines, in the United States, the United Kingdom, Continental Europe, South America, Canada. Scandinavia. Asia and Australia; and • Reinsurance- reinsurance business on a facultative and treaty basis, primarily in the United States, the United Kingdom, Continental Europe. Australia, the Asia-Pacific Region, and South Africa. Each of our business segments is composed of individual operating units that serve a market defined by geography, products, services or types of customers. Each of our operating units is positioned close to its customer base and participates in a niche market requi