Interesting slide about the cryptocurrencies Bitmain claims to hold in the context of their IPO:
https://twitter.com/Excellion/status/1028426579158884352Monero isn't explicitly mentioned, although Bitmain probably used to mine monero with their Antminer X3 I think.
Perhaps off-topic here, but I think it's also interesting to point out that they acquired 179,450 BCC between 31-DEC-17 and 31-MAR-18. That's more than the total amount of bcc that have come into circulation in that period

Like half million XMR was mined in time that Bitman mined Monero with ASIC. At best if not sold any could get half of that half million. But for sure they have plenty of XMO