A quintet of the biggest wallets on the Bitcoin blockchain have been moving around some serious amounts of BTC in the last 12 hours.

This article was first published at 11.35pm (GMT), December 4th and was updated at 6.40am December 5th:

Yesterday evening, at around 7pm (UK GMT), one of the richest wallets on the Bitcoin blockchain suddenly sprang back into action after over four years of inactivity.

The address, 1PnMfRF2enSZnR6JSexxBHuQnxG8Vo5FVK, was well-monitored as the #9 ranked account on the Bitcoin Rich List and, according to data from blockchain.com had been largely dormant for over four years. So, as you’d imagine, the clearance of the account and the movement of 66,000+ BTC (worth over $260m) immediately caused eyes to turn towards it.

🚨 🚨 🚨 🚨 🚨 🚨 🚨 🚨 🚨 🚨 66,452 #BTC (263,155,325 USD) transferred from Unknown wallet to Unknown wallet Tx: https://t.co/yhHFkujK1t — Whale Alert (@whale_alert) December 4, 2018

Then, one hour later, the 10th ranked wallet – 1AhTjUMztCihiTyA4K6E3QEpobjWLwKhkR – sprang into action after a similar period of inactivity.

🚨 🚨 🚨 🚨 🚨 🚨 🚨 🚨 🚨 🚨 66,379 #BTC (262,487,346 USD) transferred from Unknown wallet to Unknown wallet Tx: https://t.co/s06ZsBf6So — Whale Alert (@whale_alert) December 4, 2018

Were that not enough big moves for one day, at around 10pm UK time tonight, a very similar thing happened again. This time it was the – you guessed it – #11 wallet under the microscope, another one that had laid pretty idle for four years.

🚨 🚨 🚨 🚨 🚨 🚨 🚨 🚨 🚨 🚨 66,236 #BTC (260,443,654 USD) transferred from Unknown wallet to Unknown wallet Tx: https://t.co/NHa4YWXvOm — Whale Alert (@whale_alert) December 4, 2018

The action continued with another wallet worth approximately half of the first two (ranked at #30), also on the move at around 10.30pm. This was a new wallet, though, last active in July of this year.

🚨 🚨 🚨 🚨 32,957 #BTC (130,098,632 USD) transferred from Unknown wallet to Unknown wallet Tx: https://t.co/HK40R12aa0 — Whale Alert (@whale_alert) December 4, 2018

Then, at around 2am this morning, another newer wallet previously ranked #36 on that Rich List began exactly the same thing – moving another 31,269 BTC.

🚨 🚨 🚨 31,270 #BTC (122,588,823 USD) transferred from Unknown wallet to Unknown wallet Tx: https://t.co/MsWb3PybQU — Whale Alert (@whale_alert) December 5, 2018

All-in-all that’s an eye-watering 263,294 bitcoins that have shifted wallets in the last few hours from those addresses alone. At a market value of over $1.02bn, based on CryptoCompare’s current index price for Bitcoin ($3,899). To put that in some kind of context, that’s a volume of crypto that now well exceeds half of the total amount of BTC traded across exchanges in the last 24hrs.

With that amount of Bitcoin in the wild, and prices already suffering in the last few weeks, you’d probably be entitled to wonder what was going on and what it all could possibly mean. We’ll, what happened to the Bitcoin after the initial moves probably gives us a hint.

While the hot-take reaction to the first move was to fear a capitulatory dump and the further depression of the bitcoin price- and given some of the threats flying around lately, that’s not a totally unfounded fear – the second move highlighted that both tranches of coins had immediately been subdivided into smaller equally valued caches in sub-wallets after being transferred. Thus the initial transfer was split into 99 wallets each containing 662.52BTC with the 100th containing a rounded 200BTC.

When the second, and then the third did the same thing the pattern became unmissable (all the noted transfers have now been through the sub-dividing process), events began to hint that it was likely to be some kind of tidying up or prep exercise by a large hodler, and that the coins had probably been bought back from their cold storage to be rearranged in such a way as to make them more secure or accessible in the future.

As some Twitter commenters also pointed out, the move took the large bags of bitcoin from legacy wallet addresses to SegWit addresses.

Also, it was a legacy address split into segwit addresses. Clearly the behavior of an exchange moving cold storage, taking advantage of low fees, to move to segwit. My guess is @Coinbase — Mark AFV (@MarkMarkafv) December 4, 2018

This possibility was somewhat supported by others who pointed out Coinbase’s warning that it would be undertaking maintenance “that may cause movements on all Coinbase-supported blockchains”.

Right now, this seems to be the most plausible explanation – though no warnings of large movements have been posted on the pages Coinbase’s blog advised users to watch, it is telling Pro and Prime users to expect delays in Bitcoin withdrawals at the moment.

However, whether or not those coins go back to being dormant in the long term, remains to be seen – but those wallets will no doubt be being keenly observed for a while.

We have reached out to Coinbase’s support team for comment, and will update again should we get a response.