Greetings, I'm happy to announce the release of PySnpTools 4.0.22. Upgrade with: pip install --upgrade pysnptools This version offers new multithreaded reading for both the PLINK BED format and the BGEN format. On my 6 processor machine, on UK Biobank-like data, it now reads 111 giant SNPs/sec & 162M probabilities/second (was 30 SNPs and 46M probs). * Carl