日本是全球投资巨头：其金融机构持有6万亿美元海外证券，20年间翻了一倍；其中约一半投向美国资产，另有约五分之一经由开曼群岛作为主要通道转投美国。随着国内回报上升，海外资产突然回流日本的风险不再只是理论问题。
1月20日，日本30年期国债收益率升至3.8%，创近25年新高，市场在消化2月8日可能举行的突然大选及其对财政扩张的影响。研究显示，若外国投资者在某月较常态额外净卖出1400亿美元美债，短期内各期限收益率可能上升约0.5个百分点；对日本投资者而言，这相当于抛售其美债持仓的12%，也仅约占其海外证券总额的2%，除非出现全面金融恐慌否则仍不太可能，但概率已较过去上升。
海外配置结构的变化使回流更敏感：疫情后通胀推升美国短端利率并拉大与日本的差距，令货币互换对冲成本飙升，日本寿险公司的海外债券对冲比例在2021—2024年从60%降至40%。与此同时，不常对冲的养老金与投资信托扩大海外敞口：1.8万亿美元的GPIF中海外债股约占一半（2012年为22%），而因2014年税惠而走红的信托持有1.3万亿美元海外证券且多为美股；若这些无对冲资金在国内利率上行与日元走强下回流，可能推动日元升值并形成加速抛售的反馈回路，尽管30年期收益率在过去一周已从高点回落。
Japan is a global investment colossus: its financial institutions hold $6trn in foreign securities, a total that has doubled over 20 years; about half is in American assets and roughly a fifth sits in the Cayman Islands largely as a conduit for more US exposure. With domestic returns rising, the risk of a sudden repatriation shock is no longer just hypothetical.
On January 20th Japan’s 30-year government-bond yield reached 3.8%, the highest in a quarter-century, as markets priced scenarios around a snap election on February 8th and looser fiscal policy. Research suggests that if foreigners sold $140bn more Treasuries than in a typical month, yields across maturities could rise by about 0.5 percentage points in the short run; for Japanese investors that would mean dumping 12% of their Treasury holdings, equal to only about 2% of their foreign-securities stock—unlikely outside a full-blown panic, but less improbable than before.
A shift in Japan’s overseas investor mix raises sensitivity: post-covid inflation pushed US short rates far above Japan’s, making currency-swap hedges expensive, and life insurers cut hedging on foreign bonds from 60% in 2021 to 40% in 2024. Meanwhile typically unhedged players increased foreign exposure—GPIF’s $1.8trn portfolio is about 50% non-Japanese assets (up from 22% in 2012) and tax-favoured investment trusts hold $1.3trn abroad mostly in US equities—so if these investors repatriate into higher home yields and a stronger yen, the yen could appreciate and reinforce a sell-off loop, even though 30-year yields have eased from their peak in the past week.
Source: The fate of Japan’s $6trn foreign portfolio rattles global markets
Subtitle: The knock-on effects of a sell-off in Japanese-held foreign investments would be far-reaching
Dateline: 1月 29, 2026 04:18 上午 | New York