According to Reuters, Alwaleed said during a press conference in Riyadh that some of the donation would come from his own personal stake in Kingdom Holding, his investment firm, but no shares would be sold and the contribution would not affect share prices.
When questioned about the timeframe for making the donation, Alwaleed declined to give precise details. However, he said that the money would benefit organizations that promote health, disease eradication, disaster relief and women's rights.
Forbes regularly lists Alwaleed on its annual list of billionaires but has clashed with the prince over how much money he actually has. The most recent edition of Forbes' list estimated Alwaleed's personal net worth at $22.6 billion, about $10 billion less than what he has just pledged to donate.
In 2013, Alwaleed even sued the publication for underestimating his wealth on the annual list. However, Forbes responded saying that the Tadawul, the Saudi stock exchange, "is incredibly easy to manipulate."
Regardless of whether Alwaleed is worth the $32 billion he has just pledge or less as Forbes has maintained, without a precise timeframe set for the entire contribution, Alwaleed should be able to spare a few billion at a time over the next few years.