Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1,F7,F8	Jun 8, 2015	P	346,000	$23.9842	A	13,601,528	I	See Footnotes
Common Stock^F2,F7,F8	Jun 9, 2015	P	350,000	$24.6358	A	13,951,528	I	See Footnotes
Common Stock^F3,F7,F8	Jun 10, 2015	P	229,000	$25.2641	A	14,180,528	I	See Footnotes
Common Stock	holding	—	—		—	6,180	D
Common Stock^F4,F5	holding	—	—		—	1,099,046	I	See Footnotes
Common Stock^F6	holding	—	—		—	145,426	I	See Footnote

Table II — derivative securities

No Table II lines on this filing.

Explanation of responses

F1The price reported in Column 4 is a weighted average price. These shares of Common Stock were purchased in multiple transactions at prices ranging from $23.585 to $24.10. The reporting persons undertake to provide to the Staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of Common Stock purchased at each separate price within the ranges set forth in footnotes (1) through (3) of this Form 4.
F2The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $24.10 to $24.95.
F3The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $24.86 to $25.49.
F4These securities are held for the account of MHR Capital Partners Master Account LP, an Anguilla, British West Indies limited partnership ("Master Account"). MHR Advisors LLC, a Delaware limited liability company ("Advisors"), is the general partner of Master Account. MHRC LLC, a Delaware limited liability company ("MHRC"), is the managing member of Advisors. Mark H. Rachesky, M.D. ("Dr. Rachesky") is the managing member of MHRC. MHR Fund Management LLC ("Fund Management") has an investment management agreement with Master Account pursuant to which it has the power to vote or direct the vote and to dispose or to direct the disposition of the securities held for the account of Master Account. MHR Holdings LLC, a Delaware limited liability company ("MHR Holdings"), is the managing member of Fund Management. Accordingly, Advisors, MHRC, Fund Management, MHR Holdings and Dr. Rachesky may be deemed to beneficially own the securities held for the account of Master Account.
F5(continued from footnote 3) Each of Advisors, MHRC, Fund Management, MHR Holdings and Dr. Rachesky disclaims beneficial ownership of such securities except to the extent of their pecuniary interest therein.
F6These securities are held for the account of MHR Capital Partners (100) LP, a Delaware limited partnership ("Capital Partners (100)"). Advisors is the general partner of Capital Partners (100). MHRC is the managing member of Advisors. Dr. Rachesky is the managing member of MHRC. Fund Management has an investment management agreement with Capital Partners (100) pursuant to which it has the power to vote or direct the vote and to dispose or to direct the disposition of the securities held for the account of Capital Partners (100). MHR Holdings is the managing member of Fund Management. Accordingly, Advisors. MHRC, Fund Management, MHR Holdings and Dr. Rachesky may be deemed to beneficially own the securities held for the account of Capital Partners (100). Each of Advisors, MHRC, Fund Management. MHR Holdings and Dr. Rachesky disclaims beneficial ownership of such securities except to the extent of their pecuniary interest therein.
F7These securities are held for the account of MHR Institutional Partners III LP, a Delaware limited partnership ("Institutional Partners III"). MHR Institutional Advisors III LLC, a Delaware limited liability company ("Institutional Advisors III"), is the general partner of Institutional Partners III. Dr. Rachesky is the managing member of Institutional Advisors III. Fund Management has an investment management agreement with Institutional Partners III pursuant to which it has the power to vote or direct the vote and to dispose or to direct the disposition of the securities held for the account of Institutional Partners III. MHR Holdings is the managing member of Fund Management. Accordingly, Institutional Advisors III, Fund Management, MHR Holdings and Dr. Rachesky may be deemed to beneficially own the securities held for the account of Institutional Partners III.
F8(continued from footnote 7) Each of Institutional Advisors III, Fund Management, MHR Holdings and Dr. Rachesky disclaims beneficial ownership of such securities except to the extent of their pecuniary interest therein.