You're right, BTC has dumped about 12% in just one day. It seems though that the same trend happened in 2017, you can check this on the price market on coingecko and you should see that before 2017 ATH there was an initial uptrend then a down before reaching the ATH.

It is then possible that this is an event preparing for this year's ATH, or maybe not. I do, however, favour the former!