The article compares different ways to protect investments in complex financial products during a financial crisis. The researchers found that a large part of the risk in these products cannot be fully protected against. Surprisingly, simpler models sometimes work better than more complicated ones. When it comes to protecting investments, using a broad approach with the whole market is more effective than focusing on individual companies. Also, big changes in the market don't always happen when companies go bankrupt, which challenges some current ways of predicting risk.