That would raise Facebook additional billions of cash above the initial expectations of a float worth about $10bn.
But some close to the deal are worried that a higher price might lift the shares beyond the level at which experienced investors would regard as a fair value, resulting in early trading losses for new investors, damaging the reputations of Facebook and its underwriters, analysts say. According to people close to the deal, unusually strong demand by retail investors is one factor driving the price increase.
"The demand is insane," says one person at a retail brokerage. "You could write that Facebook was the worst company in the world, and retail would still want the stock.
At Facebook's IPO roadshow stop in Palo Alto, California, on Friday last week, two retail investors who were not invited to the meeting attempted to gain entry.
The brothers, aged 25 and 27, were hoping to invest $1.8m from their family's private equity fund in the Facebook IPO at any price.
"I've never been this far along in an IPO with so much uncertainty and anxiety around pricing still remaining for institutions," says one person with knowledge of the process.
Another says: "We did not expect them to raise the price."
In the past week, analysts have raised concerns over whether Facebook can justify a valuation of more than $100bn because of its slowing revenue growth and weak mobile position.
"To be a good investment for someone who likes to buy stock and hold it, you need to believe the market cap [capitalisation] can double in six years," says Steve Weinstein, managing director of ITG Investment Research.
"Right now, they're not on pace to deliver those types of financial results."
The dangers of a too-high price for new internet-related floats are fresh in investors' minds.
"There are just too many eyes on this deal," says Sam Hamadeh, a former banker and chief executive of PrivCo, a boutique research company.
Retail investors have always been key to Facebook's IPO strategy, in part because it has more than 900m users globally.
The allocation to retail investors is set to be around between 20 per cent and 25 per cent, higher than for most recent share sales, according to people briefed on the IPO.
But Facebook is also aware that wealthy individuals and day traders tend to be more prone to a quick sale, taking profits early, people familiar with its strategy say.
As Kevin Pleines, analyst at Birinyi Associates, a stock research firm, puts it: "If looking for an investment, the best course of action may be to avoid the first day of trading frenzy, and wait and see if the IPO is going to be a Google or a Groupon."