我国对银行和其他金融机构在非金融企业持股的限制对建立有效的股票市场提出了迫切的要求。然而，股票市场的发展在某种程度上被人为地限制了。我们认为，国家股和法人股不在证券市场交易而造成的发行在外的股票的难兑现性和对敌意性兼并市场的限制不仅提高了公司融资的代价而且也对降低代理成本形成了障碍。虽然名义上国家股和国有法人股是可以转让给其他法人、自然人及境内外的外商投资者，但实际上这种转让是不可能在证券市场顺利地进行的，因为这些股份的转让必须经严格而复杂的审批手续。国有企业巨大的代理成本和发行在外的股票的难兑现性大大提高了通过发行股票来融资的代价。我国法律对争夺控制权市场的限制不仅仅限于国有企业。《股票发行与交易管理暂行条例》规定，任何法人直接或间接持有上市公司发行在外在普通股达5%时，就应当自该事实发生之日起3个工作日之内，向该上市公司、证券交易所和证监会作出书面报告并公告，以后当其所持的该上市公司股份每增减2%时，就得重复这一行为。我们怀疑在我国走向市场经济的初期，证券法需对敌意性兼并做如此严格的规定。这5%的比例完全可以提高到10%以上。促进敌意性兼并市场和其他方式的企业重组有利于我国企业在投资和贸易逐步国际化和自由化的时代提高竞争能力。在我国国有企业内部监督机制微弱而产品市场又不能完全淘汰低效企业的情况下，难道还有理由去限制争夺公司控制权的市场吗？
对于因家庭控制的股份公司而可能产生的代理成本可以采取如下的政策措施：第一，要及时地推行市场自由化的进程。这包括进一步降低关税和消除其他非关税障碍。同时还需要消除严重的地方保护主义。资本和产品市场竞争的压力会促使其中的某些企业为追求规模经济等而放弃对公司的控制权。第二，对这样的公司需要增加外部董事的人数。这些董事应该和掌握公司控制权的董事无利害关系。这样有利于外部投资者掌握必要的信息。第三，对这些家庭式上市公司需要提高它们的披露义务。由于这些公司一个转移财富的行为是提高大股东支配的董事和经理的报酬，披露这些信息给市场有利于监督这些公司。需要指出的是，我国这种家庭控制型股份公司还没有普遍，但是也没有理由去限制这类公司的产生和发展。
对劳动力市场而言，我国需要做是改变过去干部式的企业领导用人制度。在这种制度下，企业领导人并无太大的压力和动力去好好经营企业。即使该企业经营不良，这些领导人还可以被调到其他企业去当官。原因是他们的干部级别必须得到保障。如果企业领导是真正的管理者，那么他们的报酬水平决定于自己的管理水平在劳动力市场上体现的价格。管理企业好的经营者可以得到较高的报酬。相反，管理水平低的经营者则只能有较低的报酬。如果他们经营的企业破了产，这些管理者甚至可能再也找不到类似的工作。只有在有效的劳动力市场上，经营管理者才有外在的压力和内在的动力去竞争，美国和日本公司治理制度的研究表明，管理者既可以完全从内部晋升，也可以从外部聘用。只要有激励和约束机制，这两种制度都有较大的监督作用。值得一提的是劳动力市场对家庭式的公司的监督作用要小得多。
四、结尾
本文讨论了由于股票融资出现的因控制权和剩余财产所有权相分离而产生的代理成本和因贷款和发行债券而产生的代理成本。当我们把注意力从代理成本问题移向控制和减少这些代理成本的监督机制时，比较公司治理制度研究就体现出了其重要意义。在我国经济体制改革不断深入的今天，比较公司治理制度研究对政策和立法都具有很大的指导作用。更好地了解因不同的公司结构和融资方法而产生的代理成本及政治、法律及市场与合同而产生的监督机制对我国公司治理改革少走弯路提供了宝贵的素材。
【作者简介】
郁光华，单位为香港大学法学院。
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