Chesapeake Energy Corporation and Bronco Drilling Company, Inc. Announce Entry into a Memorandum of Understanding in Shareholder Lawsuit

Chesapeake Energy Corporation (NYSE:CHK) and Bronco Drilling Company,
Inc. (NASDAQ: BRNC) today announced that they have entered into a
memorandum of understanding on May 17, 2011 as to the key terms of the
settlement agreement in connection with the putative consolidated class
action, captioned In Re: Bronco Drilling Company, Inc. Shareholder
Litigation (Consolidated C.A. No. 6398-VCP), pending in the Court of
Chancery of the State of Delaware.

Pursuant to the memorandum of understanding, Chesapeake and Bronco have
entered into an amendment to the pending merger agreement and Nomac
Acquisition, Inc., Chesapeake′s indirect wholly owned subsidiary, has
extended its cash tender offer to purchase all outstanding shares of
common stock of Bronco. The cash tender offer was previously scheduled
to expire at 12:00 midnight, New York City time, on Monday, May 23, 2011
and will now expire at 12:00 midnight, New York City time, on Tuesday,
May 31, 2011, unless further extended in accordance with the merger
agreement, applicable rules and regulations and the procedures described
in the Offer to Purchase. Pursuant to the cash tender offer, Nomac
Acquisition, Inc. is offering to purchase all outstanding Bronco shares
for $11.00 per share in cash, without interest and less any required
withholding taxes.

The extension of the tender offer will afford Bronco stockholders
additional time to receive and consider supplemental disclosures in the
Schedule 14D-9 filed by Bronco today in connection with the memorandum
of understanding. Accordingly, unless further extended, the tender offer
and withdrawal rights will expire at 12:00 midnight, New York City time,
at the end of the day on Tuesday, May 31, 2011. The tender offer remains
subject to satisfaction of other customary closing conditions described
in the Offer to Purchase.

The complete terms and conditions of the tender offer are set forth in
the Offer to Purchase and related Letter of Transmittal that have been
sent to holders of Bronco common stock. Copies of the Offer to Purchase
and Letter of Transmittal may be obtained at no charge from the
information agent, MacKenzie Partners, Inc., by calling (800) 322-2885
(toll-free) or (212) 929-5500 (collect). Additionally, any questions
related to the tender offer may be directed to MacKenzie Partners, Inc.
at the telephone numbers provided above.

Johnson Rice & Company L.L.C. is acting as financial advisor to Bronco.
Thompson & Knight LLP and Richards, Layton and Finger P.A. are acting as
legal advisors to Bronco. Jefferies & Company, Inc. is acting as
financial advisor to Chesapeake. Commercial Law Group, P.C. and
Wachtell, Lipton, Rosen & Katz are acting as legal advisors to
Chesapeake.

About Chesapeake:

Chesapeake Energy Corporation is the second-largest producer of
natural gas, a Top 15 producer of oil and natural gas liquids and the
most active driller of new wells in the U.S.Headquartered
in Oklahoma City, the company's operations are focused on discovering
and developing unconventional natural gas and oil fields onshore in the
U.S.Chesapeake owns leading positions in the Barnett,
Haynesville, Bossier, Marcellus and Pearsall natural gas shale plays and
in the Granite Wash, Cleveland, Tonkawa, Mississippian, Bone Spring,
Avalon, Wolfcamp, Wolfberry, Eagle Ford, Niobrara, Three Forks/Bakken
and Utica unconventional liquids plays.The company has
also vertically integrated its operations and owns substantial
midstream, compression, drilling and oilfield service assets.Chesapeake′s
stock is listed on the New York Stock Exchange under the symbol CHK.Further information is available at www.chk.com
where Chesapeake routinely posts announcements, updates, events,
investor information, presentations and press releases.

About Bronco:

Bronco Drilling Company, Inc. is a publicly held company
headquartered in Edmond, Oklahoma, and is a provider of contract land
drilling to oil and natural gas exploration and production companies.Bronco's common stock is quoted on The NASDAQ Global Select Market
under the symbol 'BRNC'.For more information
about Bronco Drilling Company, Inc., visit http://www.broncodrill.com.

Important Information:

This press release is neither an offer to purchase nor a
solicitation of an offer to sell securities. Chesapeake filed a tender
offer statement with the SEC on April 26, 2011 (which was amended by
amendments filed with the SEC on May 3, 2011, May 5, 2011 and May 17,
2011), and has mailed an offer to purchase, forms of letter of
transmittal and related documents to Bronco stockholders. Bronco has
filed with the SEC on April 26, 2011 (which was amended by amendments
filed with the SEC on May 3, 2011 and May 17, 2011), and has mailed to
Bronco stockholders, a solicitation/recommendation statement on Schedule
14D-9. INVESTORS AND BRONCO STOCKHOLDERS ARE STRONGLY ADVISED TO READ
THE TENDER OFFER STATEMENT (INCLUDING THE OFFER TO PURCHASE, LETTER OF
TRANSMITTAL AND RELATED TENDER OFFER DOCUMENTS) AND THE RELATED
SOLICITATION/RECOMMENDATION STATEMENT ON SCHEDULE 14D-9 BECAUSE THEY
CONTAIN IMPORTANT INFORMATION.

The offer to purchase, the related letter of transmittal and
certain other offer documents, as well as the
solicitation/recommendation statement, have been and will be made
available to all shareholders of Bronco at no expense to them.These
documents are also be available at no charge from the SEC's website at www.sec.gov.Free copies of these documents may also be obtained from the
Information Agent by contacting the MacKenzie Partners, Inc. at 105
Madison Avenue, New York, NY10016, or by calling (212)
929-5500 (collect) or (800) 322-2885 (toll-free).In
addition, investors and Bronco shareholders may obtain a free copy of
these documents from Bronco by contacting Bronco Drilling Company, Inc.
at 16217 N. May Ave., Edmond, OK 73013, attention: Investor Relations.

Forward Looking Statements:

This press release contains, among other things, certain
statements of a forward-looking nature. Such statements include all
statements other than those made solely with respect to historical fact.
Numerous risks, uncertainties and other factors may cause actual results
to differ materially from those expressed in any forward-looking
statement. These factors include, but are not limited to, (1) the
occurrence of any event, change or other circumstance that could give
rise to the termination of the definitive agreement; (2) successful
completion of the proposed transaction on a timely basis; (3) the impact
of regulatory reviews on the proposed transaction; (4) the outcome of
any legal proceedings that may be instituted against Chesapeake and
others following the announcement of the definitive agreement; (5) risks
that the proposed transaction disrupts current plans and operations and
the potential difficulties in employee retention as a result of the
transaction; and (6) other factors described in Chesapeake′s filings
with the SEC, including its reports on Forms 10-K, 10-Q, and 8-K.

Many of the factors that will determine the outcome of the subject
matter of this communication are beyond Chesapeake′s ability to control
or predict. Except to the extent required by applicable law, Chesapeake
does not undertake any obligation to revise or update any
forward-looking statements, or to make any other forward-looking
statements, whether as a result of new information, future results or
otherwise.

Chesapeake

Jeffrey L. Mobley, CFA, 405-767-4763

Jeff.mobley@chk.com

or

Jim
Gipson, 405-935-1310

jim.gipson@chk.com

or

Bronco

Bob
Jarvis, 405-242-4444 x-102

bjarvis@broncodrill.com