Nasdaq OMX Group (NDAQ.O) said on Friday its experiment in lowering exchange fees and rebates in 14 stocks has so far led to lower market share in those names on its exchange as many electronic market making firms sought higher rebates elsewhere. The experiment, which began on Feb. 2 and will run for at least four months, includes 14 stocks that had their associated fees lowered on Nasdaq’s exchange to 5 cents per 100 shares from 30 cents per 100 shares, and their rebates cut to 4 cents per 100 shares from 29 cents per 100 shares.