About Diadem Capital

We believe every qualified company should have access to investment opportunities without barriers or friction.

Fundraising Marketplace for Series A, Series B, Venture Debt

Diadem Capital’s Mission

Our fundraising platform matches high-growth companies with investors and lenders to make funding accessible, efficient, and frictionless.

Simplifying the fundraising process

We’re on a mission to revolutionize traditional fundraising for Founders seeking investment opportunities.

We believe Founders deserve a better path to much-needed Venture Backing, and at the same time investors need a clear route to the companies with real growth potential.

Fundraising Marketplace for Series A, Series B, Venture Debt

Creating access to capital when you need it

We give successful Founders the tools they need to supercharge their fundraising.

Our intelligent marketplace connects you with a vetted network of 600+ VCs and 100 lenders to get you the right funding at the right time.

Read our in-depth article about how we help Startups access funding.

Meet The Team


Stephanie Rieben


Stephanie spent over a decade on Wall Street starting out in investment banking at Goldman Sachs and Citigroup before jumping over to capital markets on the Equities trading floors at both Citi and later Berenberg Bank where she ran the US relationship business covering buy side clients. In 2019, she exited banking to jump into the startup world working for 2 venture backed Fintech funding platforms covering investors. In 2022, she co-founded Diadem Capital with Joe after seeing how founders were struggling to fundraise.

Born in Germany yet raised on both sides of the atlantic and an undergraduate degree from the Lausanne Hotel School in Switzerland she is trilingual. She holds an MBA from Georgetown University.

Every break she gets she loves spending with her two little boys who she’s raising in the suburbs of NYC with her French husband.


Joe Hammill


Joe spent 10 years on the trading floor at Citigroup covering both equity and credit. While at Citi, he led global projects for Citi Velocity, the #1 Wall Street web-based data and analytics platform. He’s also familiar with the founder’s journey as this is Joe’s fourth startup. When he’s not building products, Joe is likely talking about fantasy football, Josh Allen, and why this is finally the year the Bills win the Superbowl.


Sam Wiser


Sam is Diadem Capital’s founding employee and has spent years deciphering how to make raising capital more efficient. Prior to Diadem, Sam helped lead origination efforts at Hum Capital focusing on Series A-B tech-enabled companies. He graduated from the Kelley School of Business at Indiana University with a focus in Finance. An avid fisherman, you can find Sam exploring the lakes and streams of the Midwest.

Our Story

Diadem Capital was founded by Wall Street veterans turned startup operators to bring the efficiencies of the trading floor to startup fundraising.

Raising institutional capital as a startup has been and still is, largely, a relationship-based game. But there are thousands of VCs in the United States and even more startups. Navigation can be tough.

Founders scour their networks and mutual connections, cold email, attend conferences, and download LinkedIn lists all to barely move the dial. How can founders make sure their fundraises get in front of every relevant investor for their specific startup?

We looked at the “fundraising help” available to founders. Brokers and placement agents charge exorbitant retainers and fees just to cold email investors on a company’s behalf. Incumbent platforms charge thousands upfront, consistently overpromising and under delivering. For the most part these intermediaries are nonstarters for investors and above all – they don’t result in capital for founders.

We saw a better way: a platform that lightens the load so founders can dedicate more time to operating and investors see only those companies that meet the requirements of their intricate investment theses. 

Our background in Institutional Investing, Investment Banking, Trading, and Tech have led to the creation of a process that is founder aligned and VC-accepted. A hybrid approach leveraging tech while keeping personal relationships at the core of what we do. 

Diadem Capital is building the world’s largest warm introduction network, where qualified founders can quickly open the door to great investors from outside their networks.

Fundraising Marketplace for Series A, Series B, Venture Debt

“Steph and Joe were incredible. Having raised before we loved working with the Diadem Capital team. Their approach and business model are unique in the industry and made it a no-brainer decision for us to engage them. We’ve never been part of a raise where we had as many interested parties as this! This is exactly why we’ve reengaged them and we see them as a critical partner who will help us with our capital needs each step of the way.”


Mark Hadfield | CEO Persimmon Life


Our Investors and Lenders

Fundraising Marketplace for Series A, Series B, Venture Debt

Venture Capital is only a click away