After Facebook made a move in the advertising business, "Fast Money" traders debated whether its shares were a better buy than Google-parent Alphabet's stock.

The social media company said this week it will expand its ad network of third-party apps and sites to reach non-Facebook users. Traders discussed whether Facebook, which has emerged as a major advertising player, could challenge Google.

Trader Brian Kelly contended the move could send Facebook's stock higher. However, since its shares have climbed 48 percent in the last year, Facebook may make a stronger short-term trade than investment, Kelly said.

Trader Steve Grasso agreed that Facebook looks overvalued, but said he would prefer it over Alphabet.

But trader Tim Seymour touted Google as the market leader and said he would still buy its parent company's shares over Facebook.

Disclosures:

Guy Adami

Guy Adami is long CELG, EXAS, GDX, INTC, Guy Adami's wife, Linda Snow, works at Merck.

Steve Grasso

BA CC EVGN KBH MJNA MU OLN PFE PHM T TWTR GDX KIDS own EFA EFG EWJ IJR SPY NO SHORTS Stuart Frankel & CO: CAH, PHM, TEVA, AAPL, UAL, TOL, LDP, WDR, AVP, CVX, FCX, IBM, ICE, KDUS, KO, MAT, MCD, MJNA, NE, NEM, OLN, OXY, RIG, STAG, TAXI, TEX, TITXF, URI, VALE, WDR, WYNN, ZNGA, CUBA, HSPO, ICE, AMZN, MJNA, TITXF, NXTD

Brian Kelly

Brian Kelly is long Bitcoin, US Dollar; he is short Australian Dollar, Euro, EWA, EWH, FRC, Hong Kong Dollar, IWM, Yuan Short: SPY and S&P 500 Futures

Tim Seymour

Tim Seymour is long AAPL, AVP, BAC, BBRY, CLF, DO, EDC, EWZ, F, FCX, FXI, GM, GOOGL, GRMN, GE, GLNCY, INTC, LQD, M, MCD, MPEL, NKE, RACE, RAI, RH, RL, SINA, T, TWTR, UA, VALE, VZ, XOM. Tim's firm is long ABX, BABA, BIDU, CLF, EWZ, F, HD, KO, MCD, MPEL, NKE, PEP, PF, SAVE, SBUX, SINA, VALE, VIAB, WMT, WEN, YHOO, short HYG, IWM, WYNN, XRT