What's the best valuation metric for financial data and technology companies?

I'm not sure, to be honest; every time I've tried to ask a similar question I get the response, "it depends." But a good place to start is comparable transactions involving companies similar to the one you're working with. And of course any public company comps, too. There are other factors to consider--growth rates, profitability (which would juice an EBITDA multiple, of course), unique IP/patents, etc. You might also solicit a pitch from one or more investment bankers who would include thoughts on valuation and approach. Hope this helps a little bit.

It depends on whether the company is public or private. In the case of public companies, the market itself answers the valuation question. For privately held companies, the most broadly used measure is EBITDA multiple. Other measures that are important for young (unprofitable or barely profitable) companies are revenue multiples, lifetime value per customer.