我国上市公司股票期权激励效果及其影响因素研究
|
摘要
股票期权是二十世纪中叶出现的一种激励制度,它通过经理人参与剩余分享,让剩余控制权与剩余索取权相匹配,在一定程度上缓解委托代理关系,从而有效降低代理成本,使经理人的目标与股东利益最大化的目标趋于一致。正因为如此,股票期权一经产生就备受推崇。
近年来,理论界不乏关于设计、改进和推广股票期权激励机制的著述,实务界也对股票期权激励计划的激励效果进行大量检验。国外研究表明股票市场环境、相关法律法规以及上市公司股权结构对股票期权激励作用的发挥都具有重要影响。但是,理论上先进有效的激励机制引入到国内未能产生同样的效果,究其原因是由于我国资本市场不完善,股权结构不合理,业绩评价体系不科学等实施股票期权制度的基本条件缺乏。因此,我国的股票期权激励还处于摸索阶段,多家已实施的股票期权制度与国外的股票期权制度有着许多的差异,期权奖励还不能等同于国外严格意义上的股票期权。
随着股权分置改革的顺利完成和2006年《上市公司股权激励管理办法》的实施,我国上市公司股票期权激励制度的实施初步具备了企业股权结构和法律法规方面的条件。为了研究新形势下股票期权激励对于我国上市公司绩效影响,本文以2005-2007年沪深A股实施股票期权激励64家上市公司为研究对象。首先,对上市公司股票期权激励效果进行实证分析,得出股权激励水平与加权平均每股收益、扣除非经常性损益净资产收益率分别显著正相关,我国上市公司股票期权激励实施效果明显；其次,构建联立方程对股票期权激励与企业绩效内生性进行检验,检验结果表明股权激励水平与企业绩效并不存在双向因果关系；再次,进一步引入交互变量检验影响我国上市公司股票期权激励实施效果因素。研究结果表明：股权集中度与股票期权激励实施效果显著正相关,股权越集中,股票期权激励效果越好,但却与原假设不一致；国有股比例对股票期权激励实施效果的影响尚不确定；公司成长性、企业风险、市场竞争与股票期权激励实施效果显著正相关,说明在高成长性、高风险、市场竞争程度高的上市公司实施股票期权激励效果相对较好。
股票期权长期激励效应的发挥需要严格的市场条件和制度保障,结合以上结论,本文分别从政策宏观层面和企业微观层面对未来股票期权激励方案的改进提出了政策建议。最后指出本文的研究局限,并在此基础上对后续研究进行了展望。
Stock options is the middle of the twentieth century emergence of an incentive system for managers to participate in it through the remaining share, so that the remaining residual control over the match and, to some extent, ease the principal-agent relationship, in order to effectively reduce agency costs, so that managers person's goals and objectives to maximize the interests of shareholders in line. This is why stock options have on the once highly respected.
In recent years, there is no lack of theoretical circles on the design, improvement and incentive stock options to promote the writing, the practical sector of the stock option incentive plan incentive effects of a large number of tests. Study abroad shows that the stock market environment, relevant laws and regulations as well as the ownership structure of listed companies on incentive stock options have a significant impact on play. However, the theory advanced the introduction of an effective incentive mechanism to the internal failure to produce the same effect, The reason is due to China's capital markets are imperfect, equity structure is irrational, unscientific, such as performance evaluation system for the implementation of stock option system, the lack of basic conditions. Therefore, our incentive stock options is still in the exploratory stage, a number of stock options which have been implemented outside the system of stock options and a lot of difference between the system, options can not be equated with reward in the strict sense of foreign stock options.
With the split share structure reform and the successful completion in 2006, "the management of listed companies in equity-based incentives approach to" the implementation of China's listed companies incentive stock options have an initial implementation of the system of enterprise ownership structure and legal conditions and regulations. In order to study the new situation, incentive stock options for the performance of the impact of China's listed companies, this article in the Shanghai and Shenzhen A shares, 2005-2007 the implementation of incentive stock options for the 64 listed companies in the study. First of all, the stock options of listed companies to carry out empirical analysis of incentive effects, equity-based incentives to draw level with the weighted average earnings per share, excluding non-recurring gains and losses return on equity is significantly related to stock options of listed companies in China to implement effective incentive; followed by build Vierordt of incentive stock options with endogenous to enterprise performance testing, test results showed that the level of equity-based incentives and corporate performance two-way causal relationship does not exist; again, the introduction of interactive variables to further test the impact of China's listed companies to implement the effect of stock option incentive factors. The results show that:the degree of concentration of equity incentives and stock options a significant positive correlation, the more concentrated ownership, the better the effect of incentive stock options, but inconsistent with the original assumption; the proportion of state-owned shares of the stock option incentive effects of the implementation is still uncertain; the company's growth nature of enterprise risk, market competition and incentive stock options to implement a significant positive correlation in the high-growth, high risk, a high degree of competition in the market listed companies in the implementation of the incentive effect of stock options is relatively good.
Effect of long-term incentive stock options to play the market the need for strict security conditions and the system in light of these conclusions, this article from a macro-level policies and enterprise at the micro level incentive stock options for the future improvement of the program put forward policy recommendations. This study concluded that the limitations on the basis of follow-up study on the prospect.
近年来,理论界不乏关于设计、改进和推广股票期权激励机制的著述,实务界也对股票期权激励计划的激励效果进行大量检验。国外研究表明股票市场环境、相关法律法规以及上市公司股权结构对股票期权激励作用的发挥都具有重要影响。但是,理论上先进有效的激励机制引入到国内未能产生同样的效果,究其原因是由于我国资本市场不完善,股权结构不合理,业绩评价体系不科学等实施股票期权制度的基本条件缺乏。因此,我国的股票期权激励还处于摸索阶段,多家已实施的股票期权制度与国外的股票期权制度有着许多的差异,期权奖励还不能等同于国外严格意义上的股票期权。
随着股权分置改革的顺利完成和2006年《上市公司股权激励管理办法》的实施,我国上市公司股票期权激励制度的实施初步具备了企业股权结构和法律法规方面的条件。为了研究新形势下股票期权激励对于我国上市公司绩效影响,本文以2005-2007年沪深A股实施股票期权激励64家上市公司为研究对象。首先,对上市公司股票期权激励效果进行实证分析,得出股权激励水平与加权平均每股收益、扣除非经常性损益净资产收益率分别显著正相关,我国上市公司股票期权激励实施效果明显；其次,构建联立方程对股票期权激励与企业绩效内生性进行检验,检验结果表明股权激励水平与企业绩效并不存在双向因果关系；再次,进一步引入交互变量检验影响我国上市公司股票期权激励实施效果因素。研究结果表明：股权集中度与股票期权激励实施效果显著正相关,股权越集中,股票期权激励效果越好,但却与原假设不一致；国有股比例对股票期权激励实施效果的影响尚不确定；公司成长性、企业风险、市场竞争与股票期权激励实施效果显著正相关,说明在高成长性、高风险、市场竞争程度高的上市公司实施股票期权激励效果相对较好。
股票期权长期激励效应的发挥需要严格的市场条件和制度保障,结合以上结论,本文分别从政策宏观层面和企业微观层面对未来股票期权激励方案的改进提出了政策建议。最后指出本文的研究局限,并在此基础上对后续研究进行了展望。
Stock options is the middle of the twentieth century emergence of an incentive system for managers to participate in it through the remaining share, so that the remaining residual control over the match and, to some extent, ease the principal-agent relationship, in order to effectively reduce agency costs, so that managers person's goals and objectives to maximize the interests of shareholders in line. This is why stock options have on the once highly respected.
In recent years, there is no lack of theoretical circles on the design, improvement and incentive stock options to promote the writing, the practical sector of the stock option incentive plan incentive effects of a large number of tests. Study abroad shows that the stock market environment, relevant laws and regulations as well as the ownership structure of listed companies on incentive stock options have a significant impact on play. However, the theory advanced the introduction of an effective incentive mechanism to the internal failure to produce the same effect, The reason is due to China's capital markets are imperfect, equity structure is irrational, unscientific, such as performance evaluation system for the implementation of stock option system, the lack of basic conditions. Therefore, our incentive stock options is still in the exploratory stage, a number of stock options which have been implemented outside the system of stock options and a lot of difference between the system, options can not be equated with reward in the strict sense of foreign stock options.
With the split share structure reform and the successful completion in 2006, "the management of listed companies in equity-based incentives approach to" the implementation of China's listed companies incentive stock options have an initial implementation of the system of enterprise ownership structure and legal conditions and regulations. In order to study the new situation, incentive stock options for the performance of the impact of China's listed companies, this article in the Shanghai and Shenzhen A shares, 2005-2007 the implementation of incentive stock options for the 64 listed companies in the study. First of all, the stock options of listed companies to carry out empirical analysis of incentive effects, equity-based incentives to draw level with the weighted average earnings per share, excluding non-recurring gains and losses return on equity is significantly related to stock options of listed companies in China to implement effective incentive; followed by build Vierordt of incentive stock options with endogenous to enterprise performance testing, test results showed that the level of equity-based incentives and corporate performance two-way causal relationship does not exist; again, the introduction of interactive variables to further test the impact of China's listed companies to implement the effect of stock option incentive factors. The results show that:the degree of concentration of equity incentives and stock options a significant positive correlation, the more concentrated ownership, the better the effect of incentive stock options, but inconsistent with the original assumption; the proportion of state-owned shares of the stock option incentive effects of the implementation is still uncertain; the company's growth nature of enterprise risk, market competition and incentive stock options to implement a significant positive correlation in the high-growth, high risk, a high degree of competition in the market listed companies in the implementation of the incentive effect of stock options is relatively good.
Effect of long-term incentive stock options to play the market the need for strict security conditions and the system in light of these conclusions, this article from a macro-level policies and enterprise at the micro level incentive stock options for the future improvement of the program put forward policy recommendations. This study concluded that the limitations on the basis of follow-up study on the prospect.
引文
②Jensen.M.Meckling,W.H, "Theory of the Firm:Managerial behavior, Agency Costs and Ownership Structure" [J],Journal of Finance Economics,1976,3:305-360
③聂皖生：《股票期权计划：理论、方案与实务》,上海交通大学出版社,2007,p216.
④周其仁：市场里的企业：一个人力资本与非人力资本的特别合约[J].1996,6.
⑤内在激励报酬指员工从自身得到的报酬,如能够参与决策、承担更多责任、使工作更有趣等；而外在激励报酬是由企业给予员工的,包括直接报酬、间接报酬、非金钱报酬等。
⑥上市公司指的是剔除ST和金融性公司、未披露年报的沪深A股市场所有上市公司,总计1220家。
1.曹永峰.论股票期权有效激励的外部制度条件.商业时代·理论,2005,(12)：44-45.
2.陈计专.股改中股票期权激励效果的分析研究.硕士学位,武汉理工大学,2007.
3.陈文.股权激励与公司治理法律实务.法律出版社,2005.
4.陈勇,廖冠民,王霆.我国上市公司股权激励效应的实证分析.管理世界,2005,(2)：158-159.
5.高雷,宋顺林.高管人员持股与企业绩效—基于上市公司2000-2004年面板数据的经验证据.财经研究,2007,(3)：135-144.
6.顾斌,周立烨.我国上市公司股权激励实施效果的研究[J].会计研究,2007,(2)：79-80.
7.胡经生,顾磊.股票期权激励理论的最新进展及评论.企业管理,2005,(10)：18-19.
8.胡铭.上市公司高层经理与经营绩效的实证分析.财贸经济,2003,(4)：46-48.
9.黄建华,徐达,银路.股份期权—我国股权激励的一种可行形式.统计与决策,2005,(5)：16-18.
10.黄劲松.股票期权制度在我国的实践研究.学术探索,2004(7)：41-43.
11.蒋慧.我国股权激励制度实施效果分析.硕士学位论文,北京工商大学,2007.
12.李维友.经理人股票期权问题研究.东北财经大学出版社,2001.
13.李银珠.股票期权薪酬制度及其在我国的应用.会计研究,2006,(3)：80-84.
14.李豫湘,史长勇.股票期权计划及在国企中的运用探讨.商业研究,2003,(18)：126-128.
15.聂丽洁,王俊梅,王玲.基于相对EVA的股票期权激励模式研究.会计研究,2004,(10)：79-83.
16.聂皖生.股票期权计划：理论、方案与实务.上海交通大学出版社,2007.
17.牛成喆.经营者股票期权理论的分析.财会研究,2004,(4)：40-42.
18.潘亚岚,丁淑洪..国内外管理层股权激励的绩效研究综述.财会月刊,2008,(5)：69-71.
19.邱世远,徐国栋.上市公司股权激励的实证分析.统计与决策,2003,(12)：75-76.
20.石红艳.国企经营者实施股票期权激励的限制性因素分析.西北农林科技大学学报(社会科学版),2004,(1)：79-81.
21.宋增基,张宗益,朱健.上市公司经营者股权激励的影响分析.管理评论,2005,(3)：5-10.
22.宋兆刚.我国上市公司管理层股权激励的实证研究：股权激励与业绩的关系及其决定因素.硕士学位论文,山东大学,2006.
23.王国刚.我国上市公司经理人员股票期权制设计的几个要点.中国工业经济,2001,(1)：51-57.
24.王晓敏,焦永梅.上市公司管理层股票期权激励分析.管理科学文摘,2006,(1)：49-50.
25.王钰.我国上市公司股票期权激励绩效的实证研究.硕士学位,武汉理工大学,2006.
26.魏刚.高级管理层激励与上市公司经营绩效.经济研究,2000,(3)：32-39.
27.徐伟,牛津波,陈金梅.基于上市公司的经理层股权激励影响因素分析.2005,(3)：18-22.
28.于东智,谷立日。上市公司管理层持股的激励效用及影响因素.经济理论与经济管理,2001,(9)：24-30.
29.俞鸿琳.国有上市公司管理者股权激励效应的实证检验.经济科学,2006,(1)：108-116.
30.曾海辉.我国上市公司股票期权激励效应研究.硕士学位,复旦大学,2008.
31.张俊瑞,赵进文,张建.高级管理层激励与上市公司经营绩效相关性的实证分析.会计研究,2003,(9)：29-34.
32.张昕.实施股票期权激励的制度建设.财会研究,2007,(3)：48-49.
33.周海岭.我国股票期权制度的现实分析.经济师,2009,(1)：106-107.
34.周建波,孙菊生.经营者股权激励的治理效应研究.经济研究,2003,(5)：74-82.
35.周欣,郑晓齐.经理股票期权制的激励效率及其评价.经济与管理研究,2007,(3)：111-114.
36.Brain J.Hall and Kevin J.Murphy.Optimal exercise prices for executive stock options.The American Economic Review,2000, Vol.50:319-349.
37.Bryan,Bhagat and Lilien.CEO Stock-Based Compensation-An Empirical Analysis of Incentive-Intensity、Relative Mix and E conomic Determinants.Journal of Accounting and Finance,2000,Vol.73:661-693.
38.Chung Claire.E and Pruitt S.A Test of The Stock Incentives and MarketValuatio n.Finance Management,1996,Vol.18:36-64.
39.Core J,Guay W.The use of equity grants to manage optimal equity incentive levels. Journal of Accounting and Economics,1999, Vol.28,Iss,2:151-184.
40.Davies J.R,David Hillier and Patrick McColgan.Ownership Structure,Managerial Behavior and Corporate Value.Journal of Management,2005,Vol.26:375-393.
41.Defusco,Johnson and Zorn. The Effects of Stock Option and Direct Incentive on Stock Price and Firm Performance.1991,Vol.20:101-112.
42. Demsetz and Lehn.The Structure of Corporate Ownership:Causes and Conseq uences.Journal of Political Economy,1985,Vol.93:1155-1177.
43.Demsetz H and Villalonga.Ownership Structure and Corporate Performance.Journal of Corporate Finance,2001,Vol.7:209-233.
44.Hall,Brian J and Liebman,Jeffrey B.Are CEOs Really Paid Like Bureaucrats?The Quarterly Journal of Economics,1998,vol.01:653-691.
45.Himmelberg P and Glenn R, Darius.Understanding The Determinants of Manangerial Ownership and Firm Performance. Journal of Financial Economics,1999,Vol.53:127-147.
46.J.Carr Bettisa,John M. Bizjakb,Michael L. Lemmonc.Exercise Behavior, Valuation, and The Incentive Effects of Employee Stock Options.Journal of FinancialEconomics, 2005,Vol.76:445-470.
47.Jin-Chuan Duan, Jason Wei.Executive Stock Options and Incentive Effects Due To Systematic Risk.Journal of Banking & Finance,Vol.29:1185-1211.
48.Jensen,Michael C and Murphy,Kevin J. Performance Pay and Top Managemen Incentives. Journal of Political Economy,1999,Vol.98:225-264.
49.Kole,S.R.Managerial Ownership and Firm Performance:Incentive or Reward. Advance in Financial Economics,1997,vol.2:119-149.
50.Lamia Chourou,Ezzeddine Abaoubb, Samir Saadi C.The Economic Determinants of CEO Stock Option Compensation. Journal Multinational Financial Management,2008,Vol.18: 61-77.
51.Liang and Weisbenner.Who Benefits From a Bull Market? A Analysis of Employee Stock Option Grants and Stock Prices.Joumal of Finance,2002,Vol.22:303-328.
52.Tian,Yisong S. Too much of a good incentives? The case of executive stock op tions. Journal of Banking & Finance.2004,VOL.28:1225-1245.
53.Waston B and Wyatt M. Aggregation and Linearity In The Provision of Stock Incentives.Econometrica,2003,Vol.55:303-328.
③聂皖生：《股票期权计划：理论、方案与实务》,上海交通大学出版社,2007,p216.
④周其仁：市场里的企业：一个人力资本与非人力资本的特别合约[J].1996,6.
⑤内在激励报酬指员工从自身得到的报酬,如能够参与决策、承担更多责任、使工作更有趣等；而外在激励报酬是由企业给予员工的,包括直接报酬、间接报酬、非金钱报酬等。
⑥上市公司指的是剔除ST和金融性公司、未披露年报的沪深A股市场所有上市公司,总计1220家。
1.曹永峰.论股票期权有效激励的外部制度条件.商业时代·理论,2005,(12)：44-45.
2.陈计专.股改中股票期权激励效果的分析研究.硕士学位,武汉理工大学,2007.
3.陈文.股权激励与公司治理法律实务.法律出版社,2005.
4.陈勇,廖冠民,王霆.我国上市公司股权激励效应的实证分析.管理世界,2005,(2)：158-159.
5.高雷,宋顺林.高管人员持股与企业绩效—基于上市公司2000-2004年面板数据的经验证据.财经研究,2007,(3)：135-144.
6.顾斌,周立烨.我国上市公司股权激励实施效果的研究[J].会计研究,2007,(2)：79-80.
7.胡经生,顾磊.股票期权激励理论的最新进展及评论.企业管理,2005,(10)：18-19.
8.胡铭.上市公司高层经理与经营绩效的实证分析.财贸经济,2003,(4)：46-48.
9.黄建华,徐达,银路.股份期权—我国股权激励的一种可行形式.统计与决策,2005,(5)：16-18.
10.黄劲松.股票期权制度在我国的实践研究.学术探索,2004(7)：41-43.
11.蒋慧.我国股权激励制度实施效果分析.硕士学位论文,北京工商大学,2007.
12.李维友.经理人股票期权问题研究.东北财经大学出版社,2001.
13.李银珠.股票期权薪酬制度及其在我国的应用.会计研究,2006,(3)：80-84.
14.李豫湘,史长勇.股票期权计划及在国企中的运用探讨.商业研究,2003,(18)：126-128.
15.聂丽洁,王俊梅,王玲.基于相对EVA的股票期权激励模式研究.会计研究,2004,(10)：79-83.
16.聂皖生.股票期权计划：理论、方案与实务.上海交通大学出版社,2007.
17.牛成喆.经营者股票期权理论的分析.财会研究,2004,(4)：40-42.
18.潘亚岚,丁淑洪..国内外管理层股权激励的绩效研究综述.财会月刊,2008,(5)：69-71.
19.邱世远,徐国栋.上市公司股权激励的实证分析.统计与决策,2003,(12)：75-76.
20.石红艳.国企经营者实施股票期权激励的限制性因素分析.西北农林科技大学学报(社会科学版),2004,(1)：79-81.
21.宋增基,张宗益,朱健.上市公司经营者股权激励的影响分析.管理评论,2005,(3)：5-10.
22.宋兆刚.我国上市公司管理层股权激励的实证研究：股权激励与业绩的关系及其决定因素.硕士学位论文,山东大学,2006.
23.王国刚.我国上市公司经理人员股票期权制设计的几个要点.中国工业经济,2001,(1)：51-57.
24.王晓敏,焦永梅.上市公司管理层股票期权激励分析.管理科学文摘,2006,(1)：49-50.
25.王钰.我国上市公司股票期权激励绩效的实证研究.硕士学位,武汉理工大学,2006.
26.魏刚.高级管理层激励与上市公司经营绩效.经济研究,2000,(3)：32-39.
27.徐伟,牛津波,陈金梅.基于上市公司的经理层股权激励影响因素分析.2005,(3)：18-22.
28.于东智,谷立日。上市公司管理层持股的激励效用及影响因素.经济理论与经济管理,2001,(9)：24-30.
29.俞鸿琳.国有上市公司管理者股权激励效应的实证检验.经济科学,2006,(1)：108-116.
30.曾海辉.我国上市公司股票期权激励效应研究.硕士学位,复旦大学,2008.
31.张俊瑞,赵进文,张建.高级管理层激励与上市公司经营绩效相关性的实证分析.会计研究,2003,(9)：29-34.
32.张昕.实施股票期权激励的制度建设.财会研究,2007,(3)：48-49.
33.周海岭.我国股票期权制度的现实分析.经济师,2009,(1)：106-107.
34.周建波,孙菊生.经营者股权激励的治理效应研究.经济研究,2003,(5)：74-82.
35.周欣,郑晓齐.经理股票期权制的激励效率及其评价.经济与管理研究,2007,(3)：111-114.
36.Brain J.Hall and Kevin J.Murphy.Optimal exercise prices for executive stock options.The American Economic Review,2000, Vol.50:319-349.
37.Bryan,Bhagat and Lilien.CEO Stock-Based Compensation-An Empirical Analysis of Incentive-Intensity、Relative Mix and E conomic Determinants.Journal of Accounting and Finance,2000,Vol.73:661-693.
38.Chung Claire.E and Pruitt S.A Test of The Stock Incentives and MarketValuatio n.Finance Management,1996,Vol.18:36-64.
39.Core J,Guay W.The use of equity grants to manage optimal equity incentive levels. Journal of Accounting and Economics,1999, Vol.28,Iss,2:151-184.
40.Davies J.R,David Hillier and Patrick McColgan.Ownership Structure,Managerial Behavior and Corporate Value.Journal of Management,2005,Vol.26:375-393.
41.Defusco,Johnson and Zorn. The Effects of Stock Option and Direct Incentive on Stock Price and Firm Performance.1991,Vol.20:101-112.
42. Demsetz and Lehn.The Structure of Corporate Ownership:Causes and Conseq uences.Journal of Political Economy,1985,Vol.93:1155-1177.
43.Demsetz H and Villalonga.Ownership Structure and Corporate Performance.Journal of Corporate Finance,2001,Vol.7:209-233.
44.Hall,Brian J and Liebman,Jeffrey B.Are CEOs Really Paid Like Bureaucrats?The Quarterly Journal of Economics,1998,vol.01:653-691.
45.Himmelberg P and Glenn R, Darius.Understanding The Determinants of Manangerial Ownership and Firm Performance. Journal of Financial Economics,1999,Vol.53:127-147.
46.J.Carr Bettisa,John M. Bizjakb,Michael L. Lemmonc.Exercise Behavior, Valuation, and The Incentive Effects of Employee Stock Options.Journal of FinancialEconomics, 2005,Vol.76:445-470.
47.Jin-Chuan Duan, Jason Wei.Executive Stock Options and Incentive Effects Due To Systematic Risk.Journal of Banking & Finance,Vol.29:1185-1211.
48.Jensen,Michael C and Murphy,Kevin J. Performance Pay and Top Managemen Incentives. Journal of Political Economy,1999,Vol.98:225-264.
49.Kole,S.R.Managerial Ownership and Firm Performance:Incentive or Reward. Advance in Financial Economics,1997,vol.2:119-149.
50.Lamia Chourou,Ezzeddine Abaoubb, Samir Saadi C.The Economic Determinants of CEO Stock Option Compensation. Journal Multinational Financial Management,2008,Vol.18: 61-77.
51.Liang and Weisbenner.Who Benefits From a Bull Market? A Analysis of Employee Stock Option Grants and Stock Prices.Joumal of Finance,2002,Vol.22:303-328.
52.Tian,Yisong S. Too much of a good incentives? The case of executive stock op tions. Journal of Banking & Finance.2004,VOL.28:1225-1245.
53.Waston B and Wyatt M. Aggregation and Linearity In The Provision of Stock Incentives.Econometrica,2003,Vol.55:303-328.