Photography by Gary Laufman

Siminoff attributes her success to having smart people around her, both above and below. At Efficient Frontier, where she is the CEO, she gives credit where credit is due.

On her first day at Stanford Business School, Ellen Siminoff met her future husband. Not only was it a significant moment in her personal life, but it also proved fortuitous for her career. David Siminoff, now her husband of 12 years and successful businessman in his own right, quickly became Ellen’s most important professional advisor. “My husband has given me one hundred percent of my career direction,” explains Siminoff.

The Siminoffs, in fact, are Silicon Valley’s preeminent power couple. He’s a long-time prominent investor in Internet companies and she an early and high-ranking executive at Yahoo. Were it not for the classroom, the doctor’s daughter from Milwaukee who studied pre-med and economics at Princeton might very well have been just another investment banker. Having interned at Salomon Brothers during business school, Ellen was intent on accepting a job at Morgan Stanley. Instead, David persuaded her to be his partner in a company that brokered television programming in Eastern Europe.

The frontier environment of the blossoming post-Soviet bloc economies was only the first of Ellen’s experiences in booming young industries — and only the beginning of her husband’s role as career counselor. The two sold their business in 1994, and David took a job with Capital Research, the giant Los Angeles fund manager, where he invested in newspaper companies. When Ellen got an offer to help the L.A. Times build an online classifieds business, her new husband was emphatic that she accept. He was watching the fledgling Internet industry and had a hunch it was going to be big. “Dave said, ‘It’s a no-brainer. Just do it.’ ” The L.A. Times site was a precursor to Career Builder, a jobs-site consortium of several newspaper companies, and it gave Ellen an early window into the Internet.

That insight proved valuable when some business contacts of David’s approached Ellen about becoming one of the early employees at Yahoo. (Sequoia Capital, Yahoo’s venture-capital investor, has a long relationship with Capital Research.) Ellen jumped at the opportunity, though it meant leaving an established company — and moving temporarily away from David. “A boss at the L.A. Times said, ‘No one will ever fault you for going to this little company, but I’m not sure it’ll do much for your career,’ ” she says.

Joining Yahoo proved the career move of a lifetime. Siminoff rose through a series of positions to head Yahoo’s business development unit at a time when doing a deal with Yahoo was in high demand. She negotiated an early Yahoo arrangement with Google, its current nemesis. “In my defense,” she says, “I got the warrants” — a financial tool that let Yahoo later cash in a stake in Google worth hundreds of millions of dollars.

Siminoff’s husband (and father of their two young children) isn’t her only business advisor. She credits Nancy Peretsman, then at Salomon and now a top dealmaker at investment firm Allen and Company, with being her first mentor. She also attributes her success to having been able to surround herself with smart people — above and below her, she says. At Yahoo, she credits cofounder David Filo as one of the smart people higher up the corporate ladder. At her current company, Efficient Frontier, where she is the CEO, Siminoff gives credit where it’s due. “I can’t write an algorithm,” she says, referring to the mathematical formula that the engineers who work for her create to help their clients improve their Internet-advertising search results.

Having left Yahoo in 2002, Ellen Siminoff, now 39, and her chief business advisor (he’s 42) have recently changed roles. She’s at the forefront of strategy building in the online search business, and he is turning around Spark Networks, the L.A.-based company that owns dating sites such as BlackSingles.com and JDate.com. (He’s taken up flying his own plane to minimize time away from his family.)

Ellen Siminoff has some advice for anyone who wants to follow in her career footsteps: “Marry someone who is smarter than you are,” she says. “And then listen to your spouse.”

If only it were that easy.