Parexel International, a global biopharmaceutical services provider, will be acquired by Pamplona Capital Management, the two companies announced Tuesday.

The private equity firm was said to be nearing a deal to buy contract drug research firm Parexel for $4.6 billion, the Wall Street Journal reported earlier Tuesday morning.

In a press release, Parexel confirmed it will be acquired by Pamplona for $88.10 per share in cash, in a transaction valued at approximately $5 billion, which includes the pharmaceutical company's net debt.

This purchase price represents a nearly 28 percent premium to Parexel's closing stock price on May 5, the last trading day prior to published market speculation on the deal going through.

Shares of Parexel closed Monday at $83.92 apiece. The stock was climbing about 4 percent in premarket trading Tuesday following news of this deal.

"Today's announcement is the culmination of a comprehensive review of the opportunities available to the Company, including interest solicited and received from multiple parties with the assistance of independent financial and legal advisors," Parexel CEO Josef von Rickenbach said in a statement.

"Having considered these opportunities, the [Parexel] Board of Directors unanimously determined that this all-cash transaction and the significant, certain value it provides is in the best interest of [Parexel] shareholders, as well as our company."

Activist investors, including Starboard Value, have reportedly been putting pressure on Parexel to explore a sale, arguing the company's profit margins are weak.

On Tuesday, Parexel said the acquisition by Pamplona is expected to close early in the fourth quarter of 2017.

Upon completion of the transaction, Parexel will become a privately held company, and its common stock will no longer be listed on any public market.

Boston-based Parexel provides a range of services to the pharmaceutical industry, ranging from drug development and regulatory consulting, to clinical pharmacology, clinical trials management, and reimbursement.

—Reuters contributed to this reporting.

Read the full press release from Parexel.