The Beatles are rock's only million-selling act through the first half of 2020. Factoring in the modern metric of album sales plus album equivalent units ( song downloads and streaming ), The Fab Four moved 1.090 million units from January through June, according to the Nielsen's Mid-Year Report.
The Top 5 Rock List also includes...
Queen (768,000 units)
Imagine Dragons (592,000)
Fleetwood Mac (565,000)