Facebook employees and others who are contemplating when to sell their stock can get some help from a new startup called Wealthfront.

The company has created a financial planning tool that lets anyone who works in a tech company test their options for selling stock after an initial public offering.

Andy Rachleff, chief executive of Wealthfront and co-founder of Benchmark Capital, said in an interview that the company is targeting tech professionals in their 20s and 30s who are sitting on a lot of startup stock and need advice about what to do with it.

“Very few people know the answer to the question about when they should sell stock,” Rachleff said. “It’s always the No. 1 question we get from people that we work with. Another popular question is when should I exercise my stock options.”

The Wealthfront tool promises to help employees figure out the optimal plan for selling off stock. Rachleff, who has been on the boards of a lot of tech companies and is on the faculty of the Stanford University Graduate School of Business, often tells employees that they should cover their bets with an investment strategy that fits their risk profile. It might make sense to sell off 10 percent of your holdings in a post-IPO startup every quarter. Or another plan might fit.

“If you spend years working for a company, you deserve the fruits of your labor and should liquidate some of your holdings,” Rachleff said.

The tool allows folks to test various strategies against the actual stock behavior of five types of tech companies that went public in the last decade. You can tell how well each strategy would have worked with the different kinds of companies. The post-IPO trading price may increase, decrease, hit a peak and fall, or fall and recover, or simply oscillate back and forth, Rachleff said. Sometimes the best solution will be to sell all of your stock after a lock-up period ends.

You never know what pattern will happen. But you can test different strategies against different trading patterns. Since you don’t know how the trading will go, the best strategy is usually covering your bets by selling 10 percent of the stock per quarter after your lock-up period ends. That helps you benefit from multiple trading scenarios.

Wealthfront is a low-fee online financial advisor service in Palo Alto, Calif. The plan is to create a low-fee company that tech professionals and others can trust more than high-priced brokers and wealth consultants.

The company, formerly known as KaChing, has about 20 employees and has raised $10.5 million from DAG Ventures, as well as individual investments from Marc Andreessen, Ben Horowitz, Benchmark Capital’s Bruce Dunlevie and Dave Beirne, Kleiner Perkins Caufield & Byers’ Kevin Compton and Doug Mackenzie, and others.