Regardless of Michael Saylor’s repeated refusals to publish a proof of reserves for the 597,325 bitcoin (BTC) at MicroStrategy (MSTR), Coinbase CEO Brian Armstrong determined to publicly doxx their most possible location.
Disregarding Saylor’s considerations that disclosing the placement of the cash might create the chance of social engineering and wrench assaults, Armstrong tweeted about their location whereas bragging about Coinbase’s “institutional team.”
Through the thinly veiled disclosure, he admitted that eight of the highest 10 publicly traded firms with BTC on their steadiness sheets use Coinbase Prime. That makes it extremely doubtless that MicroStrategy holds BTC at Coinbase Prime.
5 good causes to suspect Michael Saylor makes use of Coinbase Prime
To begin with, MicroStrategy holds essentially the most BTC of any publicly traded firm. That already provides it an 80% probability of utilizing Coinbase Prime for its BTC, in accordance with Armstrong’s tweet this week.
Second, MicroStrategy has been the main educator of Bitcoin for Companies, offering a collection of academic supplies, coaching periods, and even internet hosting an annual convention beneath the identical identify.
If Saylor has been persistently educating executives methods to safely purchase BTC and eight of the ten largest select Coinbase Prime, it doesn’t take a lot creativeness to guess the place MicroStrategy has been shopping for BTC.
Third, on-chain monitoring of MicroStrategy’s BTC signifies a excessive chance that it’s paying Coinbase Prime Custody charges.
Arkham claims to have traced $50 billion of MicroStrategy’s $65 billion BTC — and most of it’s in Coinbase Prime Custody or has paid Coinbase Prime Custody charges throughout on-chain actions.
Fourth, MicroStrategy makes use of the BTC value on Coinbase — not different exchanges — to find out the worth of its holdings for Securities and Alternate Fee (SEC) reporting functions.
Fifth, it additionally calls Coinbase, in contrast to different exchanges or custodians, “our principal market for bitcoin.”
In different phrases, Armstrong’s tweet this week solely solidifies an already compelling suite of knowledge that MicroStrategy makes use of Coinbase Prime to retailer a considerable amount of its BTC.
Socially engineering Armstrong’s or Saylor’s workers
Social engineering is likely one of the most severe cybersecurity dangers, although the precise proportion of profitable assaults that contain social engineering can differ relying on who you ask.
A Verizon examine tallied pure social engineering assaults at 17% of knowledge breaches from November 2023 to October 2024. That determine rose as excessive as 68% once they added “human error”-style variables like clicking on a malicious hyperlink.
One other report from IBM estimated that phishing assaults rose by 84% in its most up-to-date year-over-year monitoring interval.
Coinbase itself has been the goal of assaults during which its personal workers have been a possible weak level. In Could 2025, it admitted that cybercriminals bribed customer support representatives to steal buyer information and facilitate social engineering assaults in opposition to Coinbase’s clients.
In February 2023, for instance, Armstrong’s staff printed a postmortem of an assault that focused unnamed workers with an SMS-based phishing assault. One other profitable multi-factor authentication assault drained 6,000 Coinbase accounts of their digital belongings.
Regardless of these earlier assaults, Armstrong thought-about it extra vital to brag about Coinbase’s institutional companies like Coinbase Prime.
