Found 3 exchanges where IOTA is traded for BTC. According to the data on 6 August the most optimal price to exchange MIOTA for BTC is ₿0.00000052 for 1 IOTA. This rate is fixed at CoinEx at the maximum trading volume of the pair MIOTA/BTC - 0 BTC.
The maximum daily trading volume is observed in the MIOTA/USDT trading pair at BitDelta and reaches ₿ 9.41 (0.269% of the exchange's total trading volumes) at the price ₿ 0.00000053 per 1 MIOTA.
The minimum price to buy MIOTA for BTC is 0.00000052 - on the exchange KuCoin.
The maximum price to buy MIOTA/BTC is 0.00000052 - on the exchange Gate.io.