SAP is making its largest acquisition yet as it battles start-ups, including Salesforce.com, in selling software to clients that want to better understand their customers. The $8-billion purchase of Qualtrics International, whose software gathers and analyses data, is meant to strengthen SAP\u2019s offering in the customer relations management sector. That\u2019s a field Europe\u2019s biggest software company wants to gain a stronger foothold in because it\u2019s growing faster than its core enterprise software business. Based in Utah, Qualtrics collects data on customers, brand, employees and products \u2014 such as emails, social media posts and in-app data \u2014 to give companies insights into how their customers behave or feel about them. The start-up had been planning on listing on Nasdaq in a deal with a potential valuation of up to $4.5 billion. SAP fell as much as 4.7% in early Frankfurt trading on Monday, as analysts questioned the price of the deal. It\u2019s an expensive plan to buy growth, said Neil Campling, an analyst at Mirabaud. The offer price, about 20 times Qualtrics\u2019s sales this year, is an \u201cextremely high multiple which ever way you look at it\u201d, he said in emailed comments. SAP, led by CEO Bill McDermott, has secured financing of 7 billion euros ($7.9 billion) to pay for the purchase, the company said late on Sunday. This is its largest deal to date, according to data compiled by Bloomberg, topping its 2014 acquisition of Concur Technologies for $7.2 billion. \u201cTuck-ins are tuck-ins but transformative deals are transformative deals,\u201d McDermott said on a conference call. \u201cYou\u2019d have to do a whole lot of tuck-ins and spend a whole lot of years tucking-things-in to do what we did here.\u201d SurveyMonkey, a close rival, surged as much as 67% in its trading debut in September after the online-polling start-up raised $180 million in its bigger-than-targeted US initial public offering. However, the deal was initially priced below its $2-billion valuation in a 2014 private funding round.