After a four-month climb up the L.A. radio ratings, Top 40 music station KLSX-FM (97.1) may finally be running out of momentum.

The CBS Corp.-owned station was tied with KRTH-FM (101.1) for fourth place in the market ratings released Wednesday by Arbitron Inc. Both stations claimed 3.9 percent listener share for the month.

KIIS-FM (102.7), a Top 40 music station owned by Clear Channel Communications Inc., kept the No. 1 spot with 5 percent listener share, and news station KFI-AM (640) held steady at No. 2 with 4.6 percent.

Soft rock station KOST-FM (103.5), which in May was locked in a three-way tie for fourth place with KLSX and Spanish language KLVE-FM (107.5), broke free to claim the No. 3 slot with 4.4 percent.

KLVE, which is owned by Univision Communications Inc., slipped to No. 6.

Since KLSX flipped formats from talk radio to music in February, it has shot up the ratings from around number 20. At one point it seemed poised to challenge KIIS, which has been the top-rated L.A. radio station since last year.

June marked the first month that KLSX did not see a ratings jump, and it could signify that the station’s listener base has stabilized. If true, that would mean KIIS’ crown appears safe for now.