Just to jump in: Citadel buying this portfolio says nothing about how Citadel feels about the stocks. It's the bread and butter of large HFT hedge funds; if you see someone that has to sell stock, you leverage the fact that you can buy all of it to get a discount versus the asset value. Reports are saying that Citadel was able to buy the portfolio for ~10% under the market value, all at once. That's a no-brainer because you both get a discount and avoid driving the price down by buying small pieces over the course of a week.;
If I were a betting man, I'd bet that Citadel was also selling to Situation Awareness while they were on the way up. At some point, SA had juiced their stock prices so much that no "rational" investors (those that have a view of the stock based on some amount of fundamentals) would be on the other side of the trade. It's retail investors, bandwagon investors, and Citadel-caliber funds. This situation (over-leveraged company blows up due to some volatility) happens all the time in commodities trading, which is where Citadel started.
If I were a betting man, I'd bet that Citadel was also selling to Situation Awareness while they were on the way up. At some point, SA had juiced their stock prices so much that no "rational" investors (those that have a view of the stock based on some amount of fundamentals) would be on the other side of the trade. It's retail investors, bandwagon investors, and Citadel-caliber funds. This situation (over-leveraged company blows up due to some volatility) happens all the time in commodities trading, which is where Citadel started.