The claim's core numeric details are consistently corroborated by multiple independent search snippets: the LinkedIn result titled 'The Kobeissi Letter's Post - BREAKING: Investors sold - LinkedIn' and the article result 'The US bond market was shaken, with $5.3 billion in outflows, the ...' both state that investors withdrew about $5.35 billion from U.S. investment-grade or high-grade bond funds in the week ending April 1 and attribute the data to LSEG Lipper. The Seeking Alpha result 'Weekly Commentary: A Squeeze, A Gambit, And A Z.1' further matches the 'largest since mid-April 2025' framing. However, confidence is limited because the provided X post could not be fetched directly, the corroboration came from search snippets rather than validated full-page fetches, and I did not obtain a directly fetchable Reuters or LSEG primary page in this run. The added wording 'first outflow since November and only the second in the past 12 months' is plausible but less directly corroborated than the $5.35 billion outflow figure.