A
new SEC filing of type SC 13G has appeared, disclosing an 11.3% stake in StoneCo Ltd. (ticker: STNE) of São Paulo, Brazil (14,166,748 shares of Common Stock)
None of this is attributable to Berkshire's pension funds - all is held via National Indemnity Company.
The IPO came after 30th Sep 2018 so it will not appear in the 13-F filings which are likely to be released in the middle of next week.
The price since IPO on 25th Oct has been between about $27 and $31 per share. At current price of $27.70, the stake is priced at $392 million USD. The IPO price was $24 per share, Berkhire's stake presumably having cost $340,001,952.
The
13G filing must be made within 10 business days of acquisition of a 5% stake, so it's likely to have been acquired on 25th October at IPO.