When Ariana Grande is the most established act in the top 5 of the Billboard Hot 100, it’s time to wonder what’s going on with the singles chart.

Why are all these new acts having hits? Is it coincidence or is something else going on?

The current top 5 is Iggy Azalea’s “Fancy,” featuring Charli XCX at No. 1, Magic!’s “Rude” at 2, Grande’s “Problem,” featuring Azalea, at 3; Nico & Vinz’s “Am I Wrong” at 4, and Sam Smith’s “Stay With Me” at 5.

Four of the acts in the top 5 slots are on their first Hot 100 hit as the lead act. “Problem” is Grande’s second Top 10 hit, following “The Way, featuring Mac Miller,” which reached No. 9 last spring, and her fifth song to chart in the Hot 100.

Radio guru Sean Ross believes one reason for the phenomenon is that the summer has become a more adventurous time for radio program directors.  “Summer has become the new [first quarter]; the time when hit songs with a track record somewhere else, like Nico & Vinz and Magic! are teed up for U.S. release.”  Nico & Vinz are from Norway, where “Am I Wrong”  hit No. 2, whereas Magic! are from Canada.There, the song peaked at No. 6. Azalea in Australian, but has success in the U.K. before her U.S. ascent.

Ross’s theory would also explain why the last time we saw something close to this was two years ago when Belgian-Australian singer/songwriter Gotye and Canadian Carly Rae Jepsen had such success with “Somebody That I Used To Know” and “Call Me Maybe,” concurrently with American trio fun., breaking through.

Unlike stints when we’ve had acts like Baauer and Psy in the upper reaches, whose songs were propelled more by streaming than airplay, these current acts are triple threats, all scoring well in the three pillars that comprise the Billboard Hot 100: radio play, streaming, and digital downloads.

The focus on newcomers allows veteran acts to breathe a little and gear up for Q4, “when they might possibly have a shot at selling albums,” Ross says. While superstars release albums year round, the the fourth quarter is still the most desirable time for name acts to put out new albums so they can capitalize on holiday sales. New acts seldom put out albums after September because they will be trampled by established acts.

Aiding in the success of these newbies’ success is another factor: timing: “We’re in-between major hits right now from established top 40 staples like Rihanna, Taylor Swift and Lady Gaga,” says Billboard’s associate director of charts/radio Gary Trust. “Plus, largely presumed summer smashes like Ed Sheeran’s ‘Sing’ and Katy Perry’s ‘Birthday,’ fell short of the Mainstream Top 40 chart’s top five, opening doors for songs like Azalea’s, Grande’s and the other current hits by new acts.”

Trust sums up by adding, “Pop music has always been about familiar acts and the next big thing, so perhaps at the moment, we’re simply leaning more toward the latter.”