Cryptocurrency exchanges aren't seeing a much-anticipated surge in bitcoin (BTC) purchases by retail customers using the $1,400 stimulus checks they received from the U.S. government as part of President Joe Biden's $1.9 trillion coronavirus relief bill.

The news might come as a disappointment to bitcoin bulls who speculated the latest round of "stimmy checks" might push up bitcoin prices past $60,000 or beyond. The cryptocurrency is down 11% this week after slipping 2.8% last week. It is changing hands at press time around $51,300.

The checks are still being distributed, so it might be too early to call the hyped-up episode a dud. But that's what it looks like so far. The Japanese brokerage firm Mizuho relied on a survey to estimate earlier this month that some $40 billion of the latest round of direct stimulus checks could be spent on bitcoin and stocks.

Read more: Nearly $40B in US Stimulus Checks May Be Spent on Bitcoin and Stocks: Mizuho Survey

"While it is too early to comment on the amount of money coming to our platform from the recent stimulus, we'd note that during the previous stimulus fundings, we saw significant deposits with like amounts to the individual stimulus checks," Steve Ehrlich, CEO of Voyager, a U.S. cryptocurrency exchange, told CoinDesk in an email sent by a spokesperson.

An earlier round of stimulus resulted in a spike in deposits that were exactly the same amount as the $1,200 stimulus check at the time, according to an April 2020 tweet by Brian Armstrong, CEO of Coinbase, the largest cryptocurrency exchange in the U.S.

The tweet has since been deleted, and Coinbase declined to comment on the latest round of stimulus due to the regulatory "quiet period" leading up to its public market debut. Fortunately, the tweet was preserved as a screenshot:

So the question is: Why aren't the exchanges seeing the flow?

It could be that retail traders are taking a pause after bidding up high-flying tech stocks and cryptocurrencies over the past few months. Trading volumes in call options of stocks favored by members of Reddit's WallStreetBets forum are down, according to Bloomberg.

The retail trader retreat could also be driven by macro-economic factors. Consumers are more comfortable with spending cash as the U.S. economy recovers from a pandemic-induced recession. Credit card spending among millennials spiked over the past month, according to data from JPMorgan. And that cash hasn't made its way to cryptocurrency exchanges.

It's also possible that bitcoin's doubling in prices has made the cryptocurrency look more expensive to prospective buyers.

There's still a chance a bitcoin-buying bonanza could materialize: The U.S. Internal Revenue Service expects the next batch of stimulus payments to be issued this week.

But so far? Not much to report.

Kraken, a U.S. based cryptocurrency exchange, also told CoinDesk it hasn't seen a significant uptick in $1,400 purchases.

"Many customers are adjusting their sell targets higher," wrote Kraken.