According to media reports, the reduction in the share price came as investors were doubtful about the profitability of the business in future.
Early this month, RBS launched the initial public offering (IPO) to sell a quarter of its stake or 140 million shares of Citizens to earn around $4bn and boost its balance sheet.
However, the reduced price will now allow the company to raise approximately $3bn from the sale.
RBS CEO Ross McEwan said: "The sale of Citizens is an integral part of the RBS capital plan. This IPO represents a key step on the path to full divestment.
"Selling Citizens will significantly improve our capital position and help us to create a strong and secure bank that can continue to fully support the needs of its customers."
RBS has granted an option to underwriters to purchase additional 15% shares within 30 days, which would allow it to generate $3.5bn and sell 28.75% stake in Citizens.
After closing the current IPO, RBS reportedly plans to sell another 25% stake in Citizens in next March.
Image: Citizens Financial Group has around $130bn in assets and is valued at $13.1bn. Photo: courtesy of Royal Bank of Scotland.
