In reply to Lax.

"S&M" ascends to the Hot 100's summit fueled by the first full week of digital sales for the song's "Rih-mix" featuring Britney Spears. All versions of the song, which claims the Hot 100's Digital Gainer award and becomes Rihanna's record-extending 10th No. 1 on Digital Songs, sold a combined 293,000 downloads, according to Nielsen SoundScan, a 108% increase over last week. The Spears-assisted version of the track accounted for 66% of the song's overall weekly digital sum.

Britney Spears, Rihanna Team for 'S&M Remix'
"S&M" spends a third week at No. 1 on Radio Songs (124 million audience impressions, according to Nielsen BDS

Now listed as featured artist on "S&M," Spears earns her fifth Hot 100 No. 1 and second this year, following her own "Hold It Against Me" in January. She had previously reigned with her debut single "...Baby One More Time" in 1999 and returned to the summit with "Womanizer" (2008) and "3" (2009).

"S&M" displaces Katy Perry's "E.T.," featuring Kanye West (No. 2), after three weeks atop the Hot 100. Although the song's airplay continues to build, as it spends a second week at No. 2 on Radio Songs (122 million in audience, up 13%), securing the Hot 100's Airplay Gainer nod, its digital sales decline by 12% to 284,000.