PROSPECTUS
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W. R. BERKLEY CORPORATION
COMMON STOCK
 
    Up to 75,828 presently outstanding shares (the "Shares") of Common Stock,
par value $.20 per share (the "Common Stock") of W. R. Berkley Corporation, a
Delaware corporation (the "Corporation"), may be offered for sale from time to
time by a certain stockholder of the Corporation (the "Selling Stockholder").
See "Selling Stockholder." The Corporation will not receive any of the proceeds
from the sale of the Shares by the Selling Stockholder.
 
    The Shares covered by this Prospectus may be sold by the Selling Stockholder
or by pledgees, donees, transferees or other successors in interest. Sales of
Shares by the Selling Stockholder may be effected from time to time in one or
more transactions, including block trades, in negotiated transactions or in a
combination of any such methods of sale. The selling price of the Shares may be
at the market price prevailing at the time of sale, at a price related to such
prevailing market price or at a negotiated price. The Selling Stockholder may be
deemed to be an "underwriter" within the meaning of the Securities Act of 1933,
as amended (the "Securities Act"). See "Plan of Distribution."
 
    The Corporation's Common Stock is traded in the over-the-counter market and
is quoted on the National Association of Securities Dealers Automated Quotation
("NASDAQ") National Market System under the trading symbol "BKLY." On February
5, 1996, the last sale price of the Common Stock as quoted by NASDAQ was $49 per
share.
 
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THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION NOR HAS THE SECURITIES
AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION PASSED UPON THE
ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.
 
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THE DATE OF THIS PROSPECTUS IS FEBRUARY 6, 1996.

                INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE
 
    The following documents heretofore filed by the Corporation with the
Securities and Exchange Commission (the "Commission") are incorporated herein by
reference:
 
        1. Annual Report on Form 10-K for the year ended December 31, 1994,
    filed with the Commission pursuant to Section 13 of the Securities Exchange
    Act of 1934 (the "Exchange Act");
 
        2. Quarterly Reports on Form 10-Q for the quarters ended March 31, 1995,
    June 30, 1995 and September 30, 1995, filed with the Commission pursuant to
    Section 13 of the Exchange Act;
 
        3. Current Reports on Form 8-K, dated July 20, 1995, September 14, 1995,
    September 14, 1995, November 8, 1995 and December 28, 1995, filed with the
    Commission pursuant to Section 13 of the Exchange Act; and
 
        4. The description of the Common Stock of the Corporation contained in
    the Corporation's Registration Statement on Form 8-A dated July 25, 1974,
    filed with respect to such securities pursuant to Section 12 of the Exchange
    Act, and all amendments or reports filed for purposes of updating such
    description.
 
    All reports subsequently filed pursuant to Section 13(a), 13(c), 14 or 15(d)
of the Exchange Act prior to the termination of the offering of the Shares shall
be deemed to be incorporated by reference into this Prospectus. Any statement
contained herein or in a document incorporated or deemed to be incorporated by
reference herein shall be deemed to be modified or superseded for purposes of
this Prospectus to the extent that a statement contained herein or in any
subsequently filed document which also is or is deemed to be incorporated by
reference herein modifies or supersedes such statement. Any statement so
modified or superseded shall not be deemed, except as so modified or superseded,
to constitute a part of this Prospectus.
 
    THE CORPORATION WILL PROVIDE WITHOUT CHARGE TO EACH PERSON TO WHOM THIS
PROSPECTUS IS DELIVERED, ON THE REQUEST OF ANY SUCH PERSON, A COPY OF ANY OR ALL
DOCUMENTS INCORPORATED HEREIN BY REFERENCE (OTHER THAN EXHIBITS TO SUCH
DOCUMENTS). WRITTEN REQUESTS SHOULD BE DIRECTED TO:
 
                             Robert S. Gorin, Esq.
              Senior Vice President, General Counsel and Secretary
                           W. R. Berkley Corporation
                                165 Mason Street
                                 P.O. Box 2518
                       Greenwich, Connecticut 06836-2518
              Telephone requests may be directed to (203) 629-3000
 
    No person is authorized to give any information or to make any
representations, other than those contained or incorporated by reference in this
Prospectus, in connection with the offering contemplated hereby, and, if given
or made, such information or representations must not be relied upon as having
been authorized by the Corporation or any underwriter, dealer or agent. This
Prospectus does not constitute an offer to sell or a solicitation of an offer to
buy any securities other than the securities to which it relates and does not
constitute an offer to sell or a solicitation of an offer to buy any securities
in any jurisdiction to any person to whom it is unlawful to make such offer or
solicitation in such jurisdiction. Neither the delivery of this Prospectus nor
any sale made hereunder shall, under any circumstances, create any implication
that there has been no change in the affairs of the Corporation since the date
hereof or that the information contained or incorporated by reference herein is
correct as of any time subsequent to such date.
 
    THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE COMMISSIONER
OF INSURANCE FOR THE STATE OF NORTH CAROLINA, NOR HAS THE COMMISSIONER OF
INSURANCE RULED UPON THE ACCURACY OR THE ADEQUACY OF THIS DOCUMENT.
 
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                             AVAILABLE INFORMATION
 
    The Corporation is subject to the informational requirements of the Exchange
Act and in accordance therewith files reports, proxy statements and other
information with the Commission. Such reports, proxy statements and other
information can be inspected and copied at the public reference facilities of
the Commission, Room 1024, Judiciary Plaza, 450 Fifth Street, N.W., Washington,
D.C. 20549, and at the Commission's New York Regional Office, 7 World Trade
Center, New York, New York 10048, and Chicago Regional Office, Suite 1400,
Citicorp Center, 500 West Madison Street, Chicago, Illinois 60661, and copies of
such materials can be obtained from the Public Reference Section of the
Commission at 450 Fifth Street, N.W., Washington, D.C. 20549, at prescribed
rates.
 
    This Prospectus constitutes part of a registration statement on Form S-3
(together with all amendments and exhibits, the "Registration Statement") filed
by the Corporation with the Commission under the Securities Act. This Prospectus
does not contain all of the information included in the Registration Statement,
certain parts of which are omitted in accordance with applicable regulations.
For further information pertaining to the Corporation and the Shares offered
hereby, reference is made to the Registration Statement and the Exhibits thereto
which may be inspected without charge at the office of the Commission at 450
Fifth Street, N.W., Washington, D.C. 20549, and copies thereof may be obtained
from the Commission upon payment of the prescribed fees.
 
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                                THE CORPORATION
 
    The Corporation is an insurance holding company which, through its
subsidiaries, operates in four segments of the insurance business: regional
property casualty insurance; reinsurance (conducted through Signet Star
Holdings, Inc.); specialty lines of insurance (including excess and surplus
lines and commercial transportation); and insurance services operations
(including the management of alternative insurance market mechanisms). The
Corporation's regional insurance operations are conducted primarily in the
Midwest, Southwest and Northeast sections of the United States. The reinsurance
operations, specialty insurance and insurance services are conducted nationwide.
 
    The Corporation was founded on the concept that a group of autonomous
regional and specialty insurance entities could compete effectively in selected
markets within a very large industry in order to achieve a long term competitive
advantage. Decentralized control allows each subsidiary the autonomy necessary
to respond to local or specialty market conditions while capitalizing on the
effectiveness of centralized investment and reinsurance management, and
actuarial, financial and legal staff support.
 
    The Corporation's executive offices are located at 165 Mason Street, P.O.
Box 2518, Greenwich, Connecticut 06836-2518, telephone number (203) 629-3000 The
Corporation was incorporated in Delaware in 1970 as the successor to a New
Jersey corporation incorporated in 1967.
 
                            APPLICATION OF PROCEEDS
 
    The Corporation will not receive any of the proceeds from the sale of the
Shares by the Selling Stockholder.
 
                              SELLING STOCKHOLDER
 
    The Shares offered by this Prospectus were initially issued to the Selling
Stockholder pursuant to a Stock Purchase Agreement, dated May 3, 1994 (the
"Agreement"), by and between the Selling Stockholder and the Corporation (the
"Acquisition"). Pursuant to the terms of the Agreement, the Corporation agreed
to register on Form S-3 certain shares of Common Stock of the Corporation held
by the Selling Stockholder and to keep effective such registration for such
period as may be reasonably necessary for the Selling Stockholder to dispose of
such shares. The Corporation is responsible for and will bear the costs and
expenses of preparing and maintaining such registration.
 
    Immediately following the consummation of the Acquisition, the Selling
Stockholder held 151,657 shares of Common Stock, which amount is less than 1% of
the Corporation's outstanding Common Stock. Because the Selling Stockholder may
offer pursuant to this Prospectus all or some part of the 75,828 Shares to which
this Prospectus relates, and because the offering may or may not be an
underwritten offering on a firm commitment basis, no estimate can be given as of
the date hereof as to the number of Shares to be offered for sale by the Selling
Stockholder or as to the number of shares of Common Stock that will be held by
the Selling Stockholder upon termination of such offering. See "Plan of
Distribution."
 
    The following table sets forth certain information, as of the date of this
Prospectus, with respect to the Selling Stockholder, who has not had a material
relationship with the Corporation within the past three years:
 

                                                                                NO. OF SECURITIES
  SELLING                                                                         OWNED PRIOR TO
STOCKHOLDER                                                                          OFFERING
- -----------                                                                     -----------------
                                                                             
Bobby G. Biggerstaff.........................................................         151,657

 
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                              PLAN OF DISTRIBUTION
 
    Any or all of the Shares may be sold from time to time to purchasers
directly by the Selling Stockholder. The Shares may also be offered in one or
more underwritten offerings, on a firm commitment or best efforts basis. The
Corporation will receive no proceeds from the sale of the Shares by the Selling
Stockholder.
 
    The Shares may be sold from time to time in one or more transactions at a
fixed offering price, which may be changed, or at varying prices determined at
the time of sale or at negotiated prices. Such prices will be determined by the
Selling Stockholder or by agreement between the Selling Stockholder and the
Selling Stockholder's underwriters, dealers, brokers or agents.
 
    Any underwriters, dealers, brokers or agents participating in the
distribution of the Shares may receive compensation in the form of underwriting
discounts, concessions, commissions or fees from the Selling Stockholder and/or
purchasers of Shares, for whom they may act. In addition, the Selling
Stockholder and any such underwriters, dealers, brokers or agents that
participate in the distribution of Shares may be deemed to be underwriters under
the Securities Act, and any profits on the sale of Shares by them and any
discounts, commissions or concessions received by any of such persons may be
deemed to be underwriting discounts and commissions under the Securities Act.
Those who act as underwriter, broker, dealer or agent in connection with the
sale of Shares will be selected by the Selling Stockholder and may have other
business relationships with the Corporation and its subsidiaries or affiliates
in the ordinary course of business.
 
    At any time a particular offer of Shares is made by the Selling Stockholder,
a supplement to this Prospectus will be distributed, if required, which will set
forth the aggregate amount of Shares being offered and the terms of the
offering, including the name or names of any underwriters, dealers or agents,
any discounts, commissions and other items constituting compensation from the
Selling Stockholder and any discounts, commissions or concessions allowed or
reallowed or paid to dealers. Such Prospectus supplement and, if necessary, a
post-effective amendment to the Registration Statement of which this Prospectus
is a part will be filed with the Commission to reflect the disclosure of
additional information with respect to the distribution of the Shares.
 
           DESCRIPTION OF THE CORPORATION'S OUTSTANDING CAPITAL STOCK
 
    The aggregate number of shares of capital stock of all classes which the
Corporation has authority to issue is forty-five million (45,000,000) shares, of
which forty million (40,000,000) shares are Common Stock of the par value of
twenty cents ($.20) each, and five million (5,000,000) shares are Preferred
Stock of the par value of ten cents ($.10) each. As of December 31, 1995, there
were 20,168,167 shares of Common Stock and 1,450,000 shares of Preferred Stock
outstanding.
 
COMMON STOCK
 
    Subject to the senior rights of Preferred Stock which may from time to time
be outstanding, holders of Common Stock are entitled to receive such dividends
as may be declared by the Board of Directors out of funds legally available
therefor. Upon dissolution and liquidation, holders of Common Stock are entitled
to a ratable share of the net assets of the Company remaining after payment to
the holders of the Preferred Stock of the full preferential amounts to which
they are entitled. All outstanding shares of Common Stock are fully paid and
nonassessable.
 
    The holders of Common Stock are entitled to one vote per share for the
election of Directors and on all other matters submitted to a vote of
stockholders. Holders of Common Stock are not entitled to cumulative voting for
the election of Directors. They are not entitled to preemptive rights.
 
    The transfer agent and registrar for the Common Stock is Chemical Bank.
 
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PREFERRED STOCK
 
    The Preferred Stock has priority over the Common Stock with respect to
dividends and to other distributions, including the distribution of assets upon
liquidation. The Board of Directors is authorized to fix and determine the
terms, limitations and relative rights and preferences of the Preferred Stock,
to establish series of Preferred Stock and to fix and determine the variations
as among series. The Board of Directors without stockholder approval could issue
Preferred Stock with voting and conversion rights which could adversely affect
the voting power of the holders of Common Stock.
 
    The Corporation's outstanding Preferred Stock consists of 1,000,000 shares
of Series A Cumulative Redeemable Preferred Stock and 450,000 shares of Series B
Cumulative Redeemable Preferred Stock.
 
    The Series A Cumulative Redeemable Preferred Stock was issued on January 14,
1994 in connection with the sale of 6,000,000 Depositary Shares, each
representing a 1/6 fractional interest in a share of Series A Cumulative
Redeemable Preferred Stock. The liquidation preference of each share of Series A
Cumulative Redeemable Preferred Stock is $150.00 (equivalent to $25.00 per
Depositary Share). Dividends on the Series A Cumulative Redeemable Preferred
Stock and the Depositary Shares representing such Series A Cumulative Redeemable
Preferred Stock are cumulative from the date of original issue and are payable
quarterly in arrears at the rate of 7 3/8% of the liquidation preference per
annum (equivalent to $1.84375 per annum per Depositary Share). The Series A
Cumulative Redeemable Preferred Stock and the Depositary Shares representing
such Series A Cumulative Redeemable Preferred Stock may be redeemed for cash at
the option of the Corporation, in whole or in part, at a redemption price of
$150.00 per share (equivalent to $25.00 per Depositary Share), plus accrued and
unpaid dividends, if any, thereon. The Series A Cumulative Redeemable Preferred
Stock and the Depositary Shares representing such Series A Cumulative Redeemable
Preferred Stock have no stated maturity and are not subject to any sinking fund
or mandatory redemption or convertible into or exchangeable for any other
property or securities of the Corporation.
 
    The Series B Cumulative Redeemable Preferred Stock was issued on December
28, 1995 in connection with the purchase from General Re Corporation ("General
Re") of all of the capital stock of Signet Star Holdings, Inc. owned by General
Re. As a result of a 1993 venture between the two companies, the Corporation had
owned 60% and General Re had owned 40% of Signet Star Holdings, Inc. Pursuant to
an Agreement and Plan of Restructuring, the Corporation issued to General Re
450,000 shares of Series B Cumulative Redeemable Preferred Stock having an
aggregate liquidation preference of $68,800,000. The Series B Cumulative
Redeemable Preferred Stock has a dividend rate increasing up to 6% during the
first twelve months after issuance. The rate is thereafter subject to
readjustment based on certain predetermined conditions. The Series B Cumulative
Redeemable Preferred Stock has no stated maturity and is not subject to any
sinking fund or mandatory redemption or convertible into or exchangeable for any
other property or securities of the Corporation.
 
ANTI-TAKEOVER PROVISIONS
 
    The Corporation currently has provisions in its Restated Certificate of
Incorporation and By-Laws which could have an "anti-takeover" effect. The Board
of Directors is divided into three classes, each class having a term of three
years. Each year the term of one class expires. In addition, the affirmative
vote or consent of the holders of four-fifths (80%) of the stock of the
Corporation entitled to vote in elections of Directors is required to authorize
any of the following transactions:
 
        (a) merger or consolidation of the Corporation into any other
    corporation; or
 
        (b) sale, lease, exchange, mortgage or other disposition of all or any
    substantial part of the assets of the Corporation to any other corporation,
    person or other entity; or
 
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        (c) sale or lease by any other corporation, person or entity to the
    Corporation or any subsidiary thereof of any securities or assets (except
    assets having an aggregate fair market value of less than $4,000,000) in
    exchange for voting securities (securities convertible into voting
    securities or options, warrants or rights to purchase voting securities) of
    the Corporation or any subsidiary thereof
 
if such corporation, person or entity is, or has been at any time within the
preceding two years, the beneficial owner of 5% or more of the outstanding
shares of stock of the Corporation entitled to vote in elections of Directors.
 
                                 LEGAL OPINIONS
 
    The legality of the Shares offered hereby will be passed upon for the
Corporation by Willkie Farr & Gallagher, One Citicorp Center, 153 East 53rd
Street, New York, New York 10022. Attorneys of Willkie Farr & Gallagher who have
participated in this offering beneficially own an aggregate of 49,761 shares of
Common Stock, of which 20,000 are beneficially owned by Robert B. Hodes and
29,761 are beneficially owned by Jack H. Nusbaum (which amount includes 22,750
shares held in trusts as to which Mr. Nusbaum is a co-trustee). Mr. Hodes and
Mr. Nusbaum are also Directors of the Corporation.
 
                                    EXPERTS
 
    The financial statements, schedules and selected financial data of W. R.
Berkley Corporation and subsidiaries as of December 31, 1994 and 1993 and for
each of the years in the three-year period ended December 31, 1994, incorporated
by reference in the registration statement on Form S-3 (together with all
amendments and exhibits, the "Registration Statement") have been audited and
reported upon by KPMG Peat Marwick LLP, independent certified public
accountants. The financial information for the five years ended December 31,
1994, in the table under "Selected Consolidated Financial Data" incorporated by
reference herein and in the Registration Statement has been derived from
financial statements audited by KPMG Peat Marwick LLP and has been reported upon
by KPMG Peat Marwick LLP. Such financial statements, schedules and selected
financial data have been incorporated by reference herein and in the
Registration Statement in reliance upon the reports of KPMG Peat Marwick LLP,
incorporated by reference herein, and upon the authority of said firm as experts
in accounting and auditing.
 
    The reports of KPMG Peat Marwick LLP on the financial statements, schedules
and selected financial data as described in the preceding paragraph refer to the
Company's adoption of the provisions of the Financial Accounting Standards
Board's Statements of Financial Accounting Standards No. 109, "Accounting for
Income Taxes" in 1992 and No. 115, "Accounting for Certain Investments in Debt
and Equity Securities," at December 31, 1993.
 
    The financial statements of MECC, Inc. and its subsidiary as of December 31,
1994 and 1993 and for each of the years in the three-year period ended December
31, 1994 have been incorporated by reference in the Registration Statement in
reliance upon the report of KPMG Peat Marwick LLP, independent certified public
accountants, incorporated by reference herein, and upon the authority of said
firm as experts in accounting and auditing.
 
    The report of KPMG Peat Marwick LLP on the financial statements as of
December 31, 1994 and 1993 and for each of the years in the three-year period
ended December 31, 1994 refers to MECC, Inc. and its subsidiary's adoption of
the provisions of the Financial Accounting Standards Board's Statement of
Financial Accounting Standards No. 115, "Accounting for Certain Investments in
Debt and Equity Securities," at December 31, 1993.
 
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