A financer is someone who provides money for a particular undertaking. A financier is a person or organization whose business is providing, investing, or lending money. So, in other words, a financier makes a habit of financing, while a financer might do it only once or sporadically.
Some dictionaries no longer list financer—and your spell-check may catch it—but this is a mistake. As long as finance is a verb, there will always be financers who are not financiers.
Examples
These writers use financer correctly:
He was a gunrunner and a financer of such poaching attempts. [The Times of India]
Mobley … is the sole financer of the proposed Summit Medical Compassion Center … [Providence Journal]
And these writers use financier well:
Billionaire financier George Soros is warning the United States risks something similar to the eurozone debt crisis … [AP (article now offline)]
The announcement comes a day after the World Bank (WB), the main financier of the Nairobi Urban Toll Road Project, announced it was pulling out … [The Standard]
