投资者担心，美国可能从私人市场和未上市科技领域遭遇类似于雷曼兄弟倒闭前住房泡沫破裂那样的冲击，尽管规模可能较小。由于资产不透明、流动性差，加上银行在雷曼事件后收缩了用于做空的合成产品，想系统性做空这些资产比当年做空美国住房债务更困难。

第一条路径是“胡椒面式”的做空：无法直接接触私募资产时，就做空为其提供资金的上市公司，如阿波罗、黑石、Blue Owl 和 KKR。例子是 First Brands 暴雷后，敞口较大的投行 Jefferies 股价在四周内大约下跌了 30%；做空上市 BDC 的投资者在截至 10 月 21 日的一年里获利 1.24 亿美元，而标普 BDC 指数今年已下跌 13%。

第二条路径是定制化衍生品与结构化交易，例如 QVR Advisors 的场外合约：若 OpenAI 上市或被收购的估值高于 3000 亿美元，他要按估值阶梯向对手方支付；若估值低于这一水平，则反向获利，但在公司从未上市或彻底倒闭等极端情形下，合约可能根本不会触发支付。

Investors fear the United States could face a shock similar in type, if not in scale, to the housing bust before Lehman Brothers’ collapse, this time emerging from private markets and unlisted tech firms. Because these assets are opaque and illiquid, and banks have retreated from synthetic shorting products since the Lehman crisis, systematically shorting them is even harder than shorting housing debt.

One route is a broad, indirect short: when investors cannot access private assets directly, they can short the listed financiers behind them, such as Apollo, Blackstone, Blue Owl, and KKR. In a recent case, Jefferies, exposed to the fraudulent First Brands, fell about 30% over four weeks; shorts on listed BDCs earned an estimated $124m in the year to October 21st, while the S&P BDC index is down 13% this year.

A second and third route rely on bespoke structures and syndicated loans. Over-the-counter derivatives like those offered by QVR Advisors pay off based on whether buzzy tech firms such as OpenAI end up valued above or below a $300bn threshold, though they may never trigger in non-listing or collapse scenarios. A newer tactic mimics a classic short by selling syndicated loans to banks with a delayed settlement of perhaps three months, letting investors profit if the loan price plunges, and could expand as private-credit trading becomes more liquid.