[cj]

> There will be an incoming email shortly

To the founders: ignore their email and consult your lawyer.

Trademark infringement generally requires an element of consumer brand confusion.

There is no way USPTO will see a restaurant and a stock trading app as likely to cause consumer confusion, as they are in completely different industries with absolutely no overlap. Sharing the same name doesn’t matter much given that fact.

[Matticus_Rex]

Likelihood of confusion is not an immensely high bar for nationally/internationally-known brands (or ones that wish to be nationally-known )in the age of the Internet. Your restaurant gets a string of negative BBB reviews that feature prominently on Google that were actually aimed at someone's product? That's actual harm you can point to. If Alinea were just a local restaurant instead of an internationally-known institution, it'd be one thing, but If I were the YC company I'd take the opportunity to rebrand.

[patentatt]

Observation: several posters in this very thread have expressed confusion.

Also, it's always bad form to give out legal advice on the internet.

[cj]

> several posters in this very thread have expressed confusion

Consumer confusion within a specific industry. Like a food company using their name.

If this were a food delivery startup, there would be an issue. Since it's an stock trading app, very few trademark attorneys would see an issue with it.

And of course, consult your attorney, as mentioned in the original comment.

[pvg]

ignore their email and consult your lawyer

You're making the assumption the email is a legal threat of some sort rather than an attempt to resolve the issue at hand.