Summary: Public data gives some insights into Marketo's financial history and prospects. Here’s a bit more on this week's $25 million investment in Marketo : a piece in VentureWire quotes revenue for Markteo as $4.5 Data I've collected over the years shows that Marketo had about 120 clients at the start of 2009, 325 at the start of 2010, and should end 2010 with about 800.