Cryptocurrency exchange Binance’s bitcoin (BTC) reserves dropped by $355 million last month while customer balances grew by more than $4 billion, bringing the two figures more in line with each other, according to recently published exchange reserves veri.

At the turn of the year Binance, the largest crypto exchange by trading volume, held 622,192 BTC across third-party custody and exchanges balances. On Feb 1, that figure had shrunk to 618,563 BTC. Customer net balances, in contrast, grew from 575,296 BTC to 615,816 BTC, meaning the rate of collateralization fell to 100% from 108% .

Balances of Tether’s USDT stablecoin also fell, dropping about $25 million as customer balances rose $2.6 billion.

The motive for the shift in reserves remains unclear, and Binance did not immediately respond to CoinDesk’s request for comment.

The exchange might be reallocating funds to generate a return on investment instead of over-collateralizing, and it’s worth noting that Binance remains in a healthy financial position. At current prices it holds $160 billion worth of 34 crypto assets listed on the report, all of which are held at a 1:1 or greater ratio against user balances.

Exchanges began posting proof of reserves in response to the FTX collapse in November 2022. That was prompted by a weak balance sheet comprising illiquid altcoins, eventually leading to, in effect, a bank run where the exchange couldn’t fulfill user withdrawals.

The collapse of FTX spurred a liquidation cascade across the entire industry, with bitcoin dropping to a cycle low of $16,463. It has since recovered and is was recently trading at $97,373.