Crypto Twitter is buzzing with speculation about why investors who have held bitcoins ( BTC ) for many years suddenly show signs of activity.

Investors are called “whales”, because they have large numbers of tokens stored in their digital wallets. The size of their holdings can affect the sentiment or price of a token.

data show that . The bitcoin whale transferred 360 bitcoins into one wallet, and 40 bitcoins into other wallets. The whale purchased 900 Bitcoins in 2012. He has held onto them ever since, resulting in a gain of nearly 40,000% on his initial investment.

This movement follows several whales who have moved large amounts of Bitcoin and ether ( , ETH), in the last few weeks.

After more than 10 years of inactivity, another whale wallet has moved 279 Bitcoins in April. The whale received 128 bitcoins in 2012 and 2013, when the price fluctuated from $12 to $195. The holdings now amount to $31 million.

Ether holders have also been moving their tokens. After eight years, a participant of the ether initial coin offer moved 1 ether into another wallet. The wallet contains more than 2,356 ether, purchased in the ICO at 31 cents each. The wallet is now worth over $4 million.

These whales have not been identified, nor has anyone publicly stated why they are moving.

Crypto Twitter has speculated on the silence, with reasons ranging from the developers of the dark-web site Silk Road gaining access to whales’ wallets or insiders moving tokens before bad news. Some speculated that wallet passwords of holders have been cracked.

Adam Cochran, a crypto investor, said on Twitter that “we’re seeing way too many wallets older than 10 years suddenly waking up on multiple assets.” “Unless these wallets were somehow connected to Mt Gox’s cold storage, some old wallet generator must have been cracked.”

Mt. Gox, the once largest bitcoin exchange in history, shut down in 2014, after it was revealed it had lost hundreds of thousands in bitcoin.

Cochran may have a valid argument, as hackers and online thieves have targeted old wallets repeatedly.

Taylor Monahan of MyCrypto (a wallet manager for ether) flagged earlier this month a massive “wallet-draining operation” which seemed to be affecting whales and early holders.

Monahan estimated that more than 5,000 Ether were drained in this sophisticated attack. Monahan said at the time that his best guess was that someone had a cache of data dating back a year or more and was draining keys from it.

Parikshit Nacinovich and Mark Nacinovich edited the book.