Oct 13, 2010 14:41 GMT  ·  By

According to the latest search market numbers, Google is once again gaining market share, mostly at the expense of Yahoo. In recent months, Google had seen a slow decline while Yahoo and Bing were picking up steam.

However, the comScore report for September in the US, shows that Google is on the rise, gaining 0.7 percent points, to reach 66.1 percent of the market. That's up from 65.4 in the previous month.

Google had been losing market share in the past few months, though at a very slow pace, and there are several theories as to why the trend has reversed.

Google usually sees a slight slump during the summer months as students, who are more likely to use Google, go on vacation and spend less time on their computers.

Of course, the introduction of Google Instant may have something to do with it, though, the feature should have probably driven down the number of searches not rise it.

comScore only counts the ending search for Google meaning that any intermediary results are not added to Google's monthly search volume. In theory, since users would find what they were looking for doing fewer counted searches, Google's share has gone down.

Yahoo on the other hand lost 0.7 percent points, a significant number compared to the company's share. Yahoo went from a 17.4 percent share in August to 16.7 percent in the last month.

The search engine had been starting to gain some Steam recently. September was the first full month in which Yahoo results have been powered by Bing in the US.

Finally, Bing gained a modest 0.1 percent to get to 11.2 percent of the US search market.

Note that comScore now only counts searches initiated by humans and calls this the Explicit Core Search Market. These new numbers were introduced a couple of months ago after both Yahoo and Bing started doing a lot of automated searches as part of their various properties. [via Search Engine Land]