Despite the work it's put into the search market, Microsoft has actually lost market share last month, reports ZDNet.

Search market share for Microsoft dropped to just nine percent in April, down from 10.1 percent in March. Google saw its market share rise from 53.7 to 55.2 percent. Yahoo remained stable, rising only slightly to 21.9 percent from 21.8.

Microsoft warned it wouldn't be making steady gains in search share, but was confident it could gain ground in the long-run.

AOL and Ask.com came in fourth and fifth place respectively, with search share numbers at 5.4 and 1.8 percent of the market.

More data is available at MarketingCharts.