When dustin moskovitz exited facebook at the age of 24 to work on a new start-up, he had not yet reached billionaire status.

Less than a dozen years later, his stake in the social media network has catapulted his net worth to an estimated $16bn, placing the facebook co-founder in a rarefied slice of wealth even for modern-day silicon valley.

This week, mr moskovitzs start-up, asana, became a multibillion-dollar public company in its own right, tapping into surging investor demand for business software groups. but for mr moskovitz, the listing only promises to magnify one of the central dilemmas of his life: how best to distribute his considerable wealth in his lifetime.

When we talk, we talk a lot about asana and his philanthropy, said sam altman, an entrepreneur and investor in the company.

Mr moskovitz, 36, has the appearance of a reluctant billionaire. he has been known to drive a volkswagen hatchback and fly in economy, and he extols the virtues of burning man, the desert festival that emphasises radical self-reliance and radical inclusion.

In some circles, mr moskovitz is known as the wealthiest proponent of effective altruism, a philosophy that urges followers to direct their resources to causes that will help others the most often with the aid of hard data.

As a harvard college roommate of facebook chief executive mark zuckerberg, mr moskovitz gained a reputation for his bleary-eyed efforts to expand the website beyond cambridge, massachusetts, earning the nickname the ox.

When mr zuckerberg dropped out and moved facebook to palo alto, mr moskovitz followed him out west, becoming the companys first chief technology officer.

Asana evolved from an internal project mr moskovitz developed with justin rosenstein, who has been credited with inventing facebooks like button. they billed the start-up as a solution to constant work distractions, naming it after a concept in yoga meant to convey alignment.

The online application, which counts google and nasa as clients, aims to provide a single portal for managing work tasks.

With the companys public listing, mr moskovitz has accomplished the rare feat of repeat success in silicon valley. at the end of asanas first day of trading on wednesday, the company had a market capitalisation of $4.6bn, triple its most recent valuation in private markets.

Mr moskovitz could have done anything he wanted after facebook, mr altman said. it is a grind to be a ceo of any company, especially one that has done as well as asana has.

Members of the effective altruist community are now closely watching how mr moskovitz and his wife, cari tuna, plan to disburse their wealth.

Inspired by the life you can save, the australian philosopher peter singers book about ethical giving, the couple established good ventures in 2011 to oversee their donations and investments.

Open philanthropy, which helps advise the group, maintains a public spreadsheet ranking us policy issues where it believes capital can have the greatest impact. criminal justice reform and macroeconomic stabilisation policy currently top the list.

Effective altruism has faced some pushback from critics in the non-profit world who question its cold logic, which leaves little room for passion projects.

The framework can also accommodate a wide spectrum of activities, including investments in start-ups, drawing a murky line between profit and philanthropy.

In the months leading up to asanas direct listing, mr moskovitz supplied the bulk of the companys capital, investing $450m through two convertible notes. mr moskovitz will earn interest of 3.5 per cent annually from the notes until they convert to shares in 2025.

Mr moskovitz viewed the convertible notes as a financial investment rather than an extension of his philanthropy.

For me, its an investment opportunity, said mr moskovitz. for the company, it was just an extremely competitive offer.

Mr moskovitz and ms tuna have also been drawn towards political advocacy. during the 2016 presidential election, the couple committed $20m to organisations backing democratic presidential nominee hillary clinton, becoming the third-largest public donors of the cycle.

Some members of the effective altruism community have said mr moskovitz and ms tuna advocate a reasoned approach that avoids the pitfalls of hyper-rationality.

There are a lot of times dustin pushed back and said, well, what about great opportunities that dont have the same evidence already but could be really impactful? said elie hassenfeld, chief executive of givewell, a charity assessor that works closely with good ventures.

Mr hassenfeld credited mr moskovitz with advocating for a large contribution to give directly, a non-profit that makes direct cash transfers to impoverished families in the us and africa.

The organisation recently used part of a $25m grant from good ventures to fund independent research on the effectiveness of its approach compared with typical government aid programmes, mr hassenfeld said.

It was a good example of a way that philanthropy could go to harder-to-measure activities and still end up doing a lot of good, mr hassenfeld said.

Meanwhile, mr moskovitz and ms tuna have won the endorsement of their intellectual muse.

Apart from bill and melinda gates, mr singer wrote in an email, i don't know of anyone with comparable resources who has done as much careful thinking and research into how they can use their resources to do the most good.