这或许听起来有违直觉，但私募股权离不开贷款。通常，私募股权公司的一笔投资额有超过30%为银行贷款，然后利用杠杆提高回报率。当贷款供应大减——如2009年时——私募股权公司会放缓投资步伐，不管他们已募集了多少“私募股本”。

    但杠杆融资的真正关键在于它极大地保障了下行风险。这些贷款出现在获风投企业(而非私募股权公司)的资产负债表上。如果出现贷款违约，私募股权公司只须按股权比例承担贷款银行或任何购买相关贷款的金融机构发生的贷款损失。

    因此，当上周了解到Silver Lake Partners及其投资合作伙伴在2009年底以19亿美元从eBay手中收购Skype时，曾为相关贷款提供“担保”时，我很感兴趣。

    我的初步想法有三个：

    1. 哇，他们当时一定很有信心。

    2. 可能当时没有银行愿意为这笔交易提供贷款。

    3. 为什么这么做？

    1. 是的，他们当时真的信心十足。这是Silver Lake有史以来最大的一笔投资，新成立的投资合作伙伴Andreessen Horowitz一下子用足了“单笔投资金额5万美元至5,000万美元”的限额也令其声誉受到考验。即便Skype创始人真的赢了知识产权诉讼案——他们最终达成了和解，换取部分股权——这些投资人可能也相信他们能重写所需的代码。

    2. 交易宣布时正逢信贷危机，但已开始好转。

    3. 这是最重要的问题：据接近交易的消息人士告诉我，担保是为了让贷款更便宜一些。这显然与1有关(投资人的信心)，但感觉仍是承担了不必要的高风险。每项投资都有一定的风险——正如Skype自己在IPO文件中所指——假如风险爆发，之后Silver Lake的投资者可能就不会再提供支持(不妨问问Parthenon Capital或Forstmann Little，当一笔超大规模投资出问题时会发生什么)。似乎是不必要的高风险。

    要说清楚的是，我并不是说Silver Lake无权为Skype贷款担保。大多数私募股权基金的协议中都有这样的条款，允许他们为不超过基金资金一定百分比的贷款提供担保。而且，过去也有过几宗担保案例，只不过大多都是收购价基本无关股权的扭亏为盈交易 (比如，TPG就曾为一笔仅涉及6.00美元股权的交易贷款提供担保)。而且，为贷款提供担保，也能带来一些组合管理优势，比如让投资弹药保存的时间更长一点(因为很少有基金能进行资金的反复投资)。

    但仅仅因为有权这样做，并不说明这样做就是明智的。

    我知道由于微软(Microsoft)已同意以85亿美元收购Skype，对当初Skype投资交易的任何方面提出质疑似乎都有些怪。Silver Lake的信心已得到回报，它的投资者永远都不会被要求为贷款担保支付一毛钱。

    但有一个根本原因可以解释为何私募股权的表现通常好于其他资产类别，就是很多风险都输出到了华尔街。为几个基点修正模式似乎是不必要的冒险之举。Skype应被视为例外，而并非新的常态。

    It may sound counterintuitive, but private equity is all about debt. Private equity firms typically borrow more than 30% of a deal's value from banks, and then use that leverage to juice returns. And when credit dries up -- as it did in 2009 -- PE firms slow their investment pace, no matter how much "equity" they've got lying around.

    But the real key of leveraged financing is that it seriously protects down-side risk. The loans are carried on a portfolio company's balance sheet, not on the private equity firm's balance sheet. If a default occurs, the private equity firm is only out its equity -- but the debt losses are incurred by banks or whoever else has bought the loans.

    So it was interesting to learn last week that Silver Lake Partners and its investment partners had "guaranteed" the debt for their $1.9 billion purchase of Skype from eBay (EBAY) in late 2009.

    My initial thoughts were threefold:

    1. Wow, they must have been really confident.

    2. Maybe no bank must have been willing to lend money for this deal.

    3. Why do this?

    1. Yes, they were really confident.This was the largest check Silver Lake had ever written, and infant investment partner Andreessen Horowitz was putting its nascent reputation on the line by pushing the limits of its "$50,000 to $50 million" investment strategy. Even if Skype's founders had won their legal IP claims -- they eventually settled, in exchange for an ownership piece -- the buyers likely believed they could rewrite the necessary code.

    2. The deal was announcedaround in the midst of a credit crunch, but it was easing.

    3. This is the most salient question:Sources close to the deal tell me that the guarantee was made in order to make the debt cheaper. This obviously ties into #1 (buyer confidence), but still feels like an needlessly large risk to take. Every investment carries certain risks -- as Skype itself laid out in its IPO filing -- and a blowup could have caused Silver Lake's investors to bail on subsequent support (just ask Parthenon Capital or Forstmann Little what happens when an out-sized bet goes bad). Seems like a needlessly large risk.

    To be clear, I'm not suggesting that Silver Lake didn't have the right to guarantee Skype's debt. Most PE fund agreements include provisions that allow them to guarantee debt up to a certain percentage of fund capital. And it has happened a few times before, albeit usually on turnaround transactions where the purchase price includes virtually no equity (e.g., TPG once guaranteed debt on a deal that included just $6.00 in equity). Moreover, there are some portfolio management advantages to guaranteeing debt, such as keeping dry powder drier longer (since few funds are permitted to recycle capital

    But just because you have the right to do something doesn't make it wise.

    I know that questioning any aspect of the original Skype investment seems strange in light of Microsoft's (MSFT) agreement to buy the company for $8.5 billion. Silver Lake's confidence has been rewarded, and its investors will never be asked to pay for a dime of the guaranteed debt.

    But there is a fundamental reason why private equity usually outperforms other asset classes, and it's that much of the risk is outsourced to Wall Street. Altering the model for the sake of a few basis points seems needlessly risky. Skype should be viewed as an outlier, not the new status quo.