From January 2015, she started to practice leetcode questions; she trains herself to stay focus, develops "muscle" memory when she practices those questions one by one.
2015年初, Julia开始参与做Leetcode, 开通自己第一个博客. 刷Leet code的题目, 她看了很多的代码, 每个人那学一点, 也开通Github, 发表自己的代码, 尝试写自己的一些体会.
She learns from her favorite sports – tennis, 10,000 serves practice builds up good memory for a great serve. Just keep going.
Hard work beats talent when talent fails to work hard.
1）随着国债供应持续增长，对冲基金基差头寸同样持续增长，任何外部冲击可能引发更严重的流动性危机。2）美国国债市场的脆弱性来源于三个方面，即对冲基金高杠杆基差交易、经纪交易商缓冲能力有限以及国债供应增长加剧脆弱性。其中，对冲基金通过高杠杆进行国债现券-期货基差交易，是市场脆弱性的主要来源。3）尽管调整杠杆率、提高初始保证金等传统政策工具可以改善美债市场脆弱性，但是仍有诸多局限。相比传统政策工具，Kashyap et al.（2025）建议美联储在购买国债的同时，通过卖空期货对冲利率风险，保持久期中性。这种操作仅提供流动性支持，且不改变货币政策立场
根据Kashyap et al.（2025），美债基差交易中有三大参与者，即资产管理者（Asset Manager）、对冲基金（Hedge Fund）以及经纪交易商（Dealer）。资产管理者的衍生品需求推高基差，吸引高杠杆对冲基金套利，而交易商受限于资本约束，在压力时期无法充分吸收平仓冲击，导致市场功能恶化。
根据Kashyap et al.（2025），美债基差交易中有三大参与者，即资产管理者（Asset Manager）、对冲基金（Hedge Fund）以及经纪交易商（Dealer）。资产管理者的衍生品需求推高基差，吸引高杠杆对冲基金套利，而交易商受限于资本约束，在压力时期无法充分吸收平仓冲击，导致市场功能恶化。
国债供应的持续增加将促使对冲基金在国债-期货基差交易中持有更大的杠杆头寸。资产管理者（Asset Manager）需通过期货延长久期，推高对冲基金（Hedge Fund）以及经纪交易商（Dealer）的套利需求。根据Kashyap et al.（2025）的实证结果，国债发行量每增加100亿，对冲基金期货空头头寸扩大5亿。
（四）如何应对基差交易的风险？
1、传统政策工具的局限性
根据Kashyap et al.（2025），尽管调整杠杆率、提高初始保证金等传统政策工具可以改善美债市场脆弱性，但是仍有诸多局限。具体来看，1）调整杠杆率可缓解交易商压力，但实证表明其效果有限（Cochran et al.,2023），且无法解决基差交易的根本脆弱性。2）扩大回购工具覆盖范围允许非银机构（如对冲基金）直接使用美联储回购工具可改善融资压力，但无法应对资本冲击驱动的平仓（如保证金上调或投资者赎回）。3）设定最低保证金要求通过提高初始保证金可抑制杠杆，但无法消除周期性保证金上调的放大效应，且需动态调整监管规则以应对压力情景。4）中央清算虽能通过跨保证金降低基差交易成本，但无法阻止由资本冲击引发的强制平仓，对市场流动性危机的缓解作用有限。
2、对冲式购买的四大优势
相比传统政策工具，Kashyap et al.（2025）建议美联储在购买国债的同时，通过卖空期货对冲利率风险，保持整体久期中性。这种操作仅提供流动性支持，不改变货币政策立场。且具备四大优势：1）明确区分市场功能与货币政策，避免2020年量化宽松混淆政策目标的教训，防止市场误读利率信号；2）无需预设退出时间表，可根据市场恢复情况灵活平仓；3）降低利率风险暴露，避免美联储因持有未对冲国债而承担潜在损失；4）缓解道德风险，对冲操作不会创造“Fed Put”，减少对冲基金过度冒险的动机。
Sarah Wynn Williams is a Director of Public Policy at Facebook. She works on global public policy with a focus on LATAM, Canada, and the APAC regions.
Sarah is an experienced diplomat, policy expert, and international lawyer. She managed the political affairs and government relations office at the New Zealand embassy in Washington, DC from 2007-2011. From 2002-2007, she served as a policy adviser in the New Zealand government on environment, sustainability and security issues and worked on the ratification of complex international treaties. During this time, Sarah was asked to serve as the Chief Negotiator for the United Nations on biosafety liability. She also worked on international security, international law, and human rights at the United Nations General Assembly. In addition she was an adjunct law lecturer at Victoria University. Prior to that, she practiced law at Mallesons, Stephen, Jacques law firm in Sydney, Australia and was seconded to Niue’s Attorney General’s Office to work on counterterrorism measures and human rights issues in Niue.
Most recently, Sarah was Head of Relations with the World Bank and IMF for Oxfam International. Sarah earned a BA in political science, international relations and diplomacy from University of Canterbury and a Master of Laws from Victoria University.
彭博社则引述市场分析指出，川普在宣布暂缓关税的3个半小时前，曾于社群平台呼吁支持者“这是买入的好时机”，引发干预市场的质疑。Aptus Capital Advisors基金经理瓦格纳（David Wagner）表示，川普此举“几乎是直接干预市场”，但坦言川普的作风向来不按常理出牌，“我们只能解读他释放出的讯号”。
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(Bloomberg) — Short sellers, or traders who wager on share price declines, are up $159 billion in paper profits over just six trading days after an escalating trade war sent the US stock market plummeting down more than 10%.
The biggest market drawdown since 2022 on President Donald Trump’s pronouncement of sweeping worldwide tariffs made bets against an exchange traded fund tracking the S&P 500 Index, known as SPY, the most profitable short bet in that timeframe, according to data from S3 Partners LLC. Traders wagering that the ETF would fall have so far accumulated paper profits of more than $6.1 billion this month, per an S3 report Tuesday.
Shorts stand to benefit from the wild intraday swings that erased trillions of dollars of market value, though it will ultimately depend on when they cash out on their wagers. With another $46 billion of new short bets made in April, according to S3, there’s a risk those contrarian wagers further amplify the next big shift in the market, especially if current weakness reverses and sends the major indexes higher.
“Overall, the short side was an extraordinarily profitable trade up and down the market during this correction,” Ihor Dusaniwsky, managing director of predictive analytics at S3, wrote. “81% of every short trade was profitable and 97% of every dollar shorted was a profitable trade.”
Other contrarian bets that netted shorts the most gains include Apple Inc., Nvidia Corp and Tesla Inc. The Invesco QQQ Trust Series, which tracks the Nasdaq 100 Index, rounds out the top five most-profitable short trades so far in April. Each of the top five has so far netted paper profits of more than $2 billion for short sellers.
Most of the so-called Magnificent Seven megacap technology stocks are included in the list of most profitable shorts so far in April. Meta Platforms Inc, Amazon.com and Microsoft Corp. are also in the top fifteen. Outside of Nvidia, shorts have made solid bets that share prices of Advanced Micro Devices Inc., Broadcom Inc. and Micron Technology Inc. would decline.
Total short interest, or the dollar amount of total shares sold short, decreased by $114 billion — in part due to falling equity prices. In the event of a market rebound, short sellers will likely exit their negative positions by buying back shares, which could boost upside momentum for the overall market.
“When the market hits a floor and starts trending upwards again, we should expect a slew of buy-to-covers as the mark-to-market increase of shares shorted creates a short side over-exposure in hedged portfolios and short sellers look to realize their mark-to-market gains,” said Dusaniwsky. “Short sellers will be shoulder to shoulder with momentum and FOMO traders buying into a future rally, exacerbating market volatility on the way up as they did on the way down.”
More stories like this are available on bloomberg.com
