Ex-business partner started competing company with almost identical name - what are my options?

I co-founded a marketing agency called "Spark Digital Marketing" in San Francisco 5 years ago. My partner and I had a falling out last year and he left. We didn't have a formal partnership agreement (I know, stupid mistake).

Now I just discovered he's started a new agency called "Digital Spark Marketing" in the same city, targeting the same clients. He's even reaching out to OUR existing clients, and at least one has told me they were confused and thought it was us with a rebrand.

Do I have any legal recourse? I never registered a trademark but I've been using the name for 5 years. This feels like he's deliberately trying to steal my business.

The partnership ended badly. He basically stopped showing up and contributing, so I told him it wasn't working. He said "fine" and walked away. No formal dissolution, no buyout. He just left. I kept running the business, kept the clients, kept the name.

That was about 14 months ago. He started his new "Digital Spark Marketing" about 3 months ago based on the LLC filing date I found.

Started the trademark application process today. Also consulting with an IP attorney this week about the C&D letter.

The 14-month gap is actually helpful for you. If he wanted to claim rights to the name, he would have done so when he left. By walking away and not asserting any claim for over a year, he essentially abandoned any rights he might have had.

Then starting a NEW company with a DIFFERENT (but similar) name shows he knew he couldn't just use your exact name. He's trying to get as close as possible without being identical. That's the behavior of someone who knows they're in a gray area.

Marketing consultant here, not a lawyer. Beyond the legal stuff, think about the practical business side too.

Reach out to your existing clients proactively. Let them know about the situation (professionally, without badmouthing). Something like "We've become aware that there's a new company with a similar name in the area. Just to be clear, we are still Spark Digital Marketing, and any communications from 'Digital Spark Marketing' are NOT from us."

This protects your client relationships and also creates documentation of actual confusion in the marketplace, which strengthens any legal claim.

This thread is a masterclass in why partnership agreements matter. The $12K in legal fees for this dispute probably would have been avoided with a $2-3K partnership agreement upfront that addressed IP ownership and non-compete terms.

For anyone starting a business with a partner right now: get it in writing. Use the partnership agreement template on this site as a starting point idk, then have an attorney customize it. Future you will thank present you smh.

Going through something vaguely similar - not a partner but a former employee who started a competing business with a suspiciously similar name. Different industry (landscaping) but same playbook. This thread has been so helpful for understanding my options.

Quick question for the attorneys: does it matter that my former employee signed a non-compete? He claims it's not enforceable in Colorado.