The chief executive of German business software maker SAP has fiercely defended the $129-per-share deal it has sealed to buy U.S.-based expense management software maker Concur Technologies, telling CNBC that "I absolutely feel very comfortable that it's a fair price."Â
The software and cloud computing company announced Thursday that it had agreed to acquire Concur in an all-stock deal valued at $7.3 billion -- Â a 20 percent premium over the Wednesday closing price.
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With the acquisition of Concur, the biggest in SAP's history, SAP will increase its cloud users to 50 million from 38 million currently.Â
But with Concur's stock  trading at 12 times revenue, the  company has come under criticism from analysts that it has paid too high a price.
SAP chief executive Bill McDermot rejected the criticisms, claiming "It's not what you pay for assets in this market, it's what you do with them."
"I never was more confident in any business case I presented in the boardroom than with Concur and SAP."
Read MoreSAPÂ agrees to buy software maker Concur for $7.3B
Concur has 23,000 clients, including companies, governments and universities, with more than 25 million users of its business expense and travel management software and services.
McDermott explained the deal would improve traveller's experience: Â "Travellers all over the world are in pain. Â Very few travellers are happy with their travel and expense reporting system. Concur changes the game."
Fair disclosure: Concur supplies expense management software to CNBC.