Matt Levine's Bloomberg column discussed this contemporaneously (https://www.bloomberg.com/opinion/articles/2018-02-14/is-vix-manipulated-or-hedged https://www.

Matt Levine's Bloomberg column discussed this contemporaneously (https://www.bloomberg.com/opinion/articles/2018-02-14/is-vix-manipulated-or-hedged https://www.bloomberg.com/opinion/articles/2018-02-14/is-vix...). For Credit Suisse (issuer of XIV), hedging their exposure to XIV allegedly required buying volatility futures when the price increased. With limited liquidity, this moved the futures prices themselves. Credit Suisse has been sued (https://www.institutionalinvestor.com/article/b1rlv9r030854q/Market-Manipulation-Case-Reopening-Adds-to-Credit-Suisse-s-Woes https://www.institutionalinvestor.com/article/b1rlv9r030854q...). This collective price response wasn't a short squeeze, but instead it was closer to a gamma squeeze. It didn't rely on finite supply of any security, just limited liquidity and trade sizes large enough to move the market price.