More than $1 billion has flowed out of spot exchange-traded funds (ETFs) tracking ethereum this month.

Cointelegraph, a blockchain media outlet, reported on Oct. 21 that cumulative net outflows from ethereum spot ETFs in October were tallied at $1.08 billion. It was the biggest amount this year and the largest monthly net outflow since November last year.

About $26 million flowed in on Oct. 20, but it was not enough to offset the month-to-date net outflows. Cumulative net inflows since the start of the year also fell to about $485 million. That means money that flowed in during September left within a month.

Prices also stayed weak. Ethereum started October at around $2,700, but fell to above $2,438 on the day, down about 10 percent. The decline for the year is about 18 percent. As ETF outflows coincided with the price drop, concerns grew about slowing institutional demand.

By contrast, bitcoin spot ETFs posted net inflows of $527 million on Oct. 20, followed by net inflows of $23 million on Oct. 21. Still, October as a whole remained in net outflow of about $67 million, while cumulative net inflows since the start of the year were tallied at about $809 million.

Bitcoin traded at around $82,954 on the day and fell 2.2 percent since Oct. 1. The decline for the year was 5.3 percent. The drop was smaller than ethereum's, but the trend showed that ETF inflows do not immediately translate into a price rebound.

Even so, it is difficult to gauge demand across the broader cryptocurrency market based on ETF flows alone. Because both retail and institutional money flows into ETFs, net outflows cannot be immediately concluded as an exit by institutional investors. Examining spot-market trading volume and changes in derivatives positions together is needed to distinguish whether buying has weakened overall or investment routes have shifted.

The market is watching whether flows will reverse during the remaining trading days. Ethereum spot ETFs have already erased most of the money that flowed in during September, and bitcoin spot ETFs are also failing to fully make up for monthly weakness with only some daily inflows. If the direction of ETF flows holds through the end of October, additional changes in the year-to-date cumulative inflow totals appear unavoidable.