According to a Friday report by research firm comScore, Google witnessed a second consecutive monthly decline in its Internet search market share, with its figures for the month of May falling to 63.7 percent. Meanwhile, the combined share of Google’s rivals – Yahoo and Microsoft – reached 30.4 percent during the month.

Despite the fact that some analysts have expressed the opinion that the statistics tend to somewhat overstate the Internet search market gains made Yahoo and Microsoft, the two companies have also individually shown an increase in their respective share of the market.

Nonetheless, noting that a Yahoo-Microsoft revenue sharing deal is close at hand – with Microsoft set to serve up search and advertising results on Yahoo pages by the year-end -, analyst Ben Schachter, at Broadpoint AmTech, cautioned that the “contextual shortcuts” used by Yahoo and Microsoft have likely skewed comScore’s May statistics.

As per Schachter’s research note to clients, after backing out the Yahoo-Microsoft shortcuts, the combined search market share of the two companies likely fell to 27.4 percent in May; with Google’s share having increased to 66.4 during the month.

In concurrence with Schachter’s note, Jefferies & Co. analyst Youssef Squali too wrote to clients that comScore’s May statistics are likely to cause “confusion” because “most of Yahoo and Microsoft Bing’s gains came from a cosmetic change.”