Booz Allen said Tuesday the transaction is valued at $29.88 per share — the firm’s Tuesday closing figure — and the sale will close by Monday.
Credit Suisse will offer the shares periodically on the New York Stock Exchange, over-the-counter markets, through negotiated transactions or other methods.
Carlyle Group last cut its Booz Allen stake to 29 percent in February through a sale of 12 million shares to Morgan Stanley & Co.
Prior to that in November 2014, Carlyle reduced its stake to 37 percent when the firm sold 10 million shares to J.P. Morgan.
Shares in Booz Allen are up 12.63 percent from the year’s start and have risen 12.75 percent over 12 months.