The eBay and StumbleUpon union came to an end on Monday after the social networking sites founders bought back the company, two years after being ebay bought them for $75 million.

eBay said the decision came after the two companies failed to find a long-term, strategic synergies between the units.

In a blog post by StumbleUpon, co-founders Garrett Camp and Geoff Smith said that the company is now a startup again and said they bought back the company with a group of investors, including Accel Partners and August Capital. Financial terms of the deal were not disclosed.

We are grateful to eBay for its guidance. However, we realized there were few long-term synergies between the two businesses. It is best for us to part ways and focus on our respective strengths, Camp said in a statement. This change makes it possible for StumbleUpon to continue to innovate and focus on becoming the Web's largest recommendation service.

StumbleUpon was founded in 2001 and has now more than 7.4 million users. It allows users to rank a web page by using a thumbs up/thumbs down and makes it easy to share links with other users.

eBay has also been heavily scrutinized for its $2.6 billion acquisition of Skype in 2005 which has also been criticized as a deal that never achieved the synergies that executives originally promised and is speculated to also be sold off. eBay Chief Executive John Donahoe told analysts last week that he would not force synergies where they don't exist.

Meanwhile, EBay recently said it would focus on bolstering its PayPal online payments business and focus on driving growth across its various e-commerce platforms.

eBay closed down 39 cents or 2.6 percent to $14.63.

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