Some stablecoins are fractionally backed, meaning that if, say, $100 million in stablecoins have been issued, there may be only $70 million in the corresponding treasury backing it up. In that case, if 70% of the stablecoin holders redeemed their tokens, things would be fine. But if 80% redeemed their tokens, it would become a problem. For FRAX and other similar stablecoins, algorithmic stabilization methods are used to “maintain the peg.” That is, to make sure the exchange value of the stablecoin remains very close to that of the USD peg.