Robert Half shares gained 29.0% during a five-day winning streak.
The rally added approximately $936 million to the company's market capitalization.
The firm's total market value now stands at about $4.2 billion.
Bessemer Group Inc. increased its stake in the company by 29.5% during the first quarter.
The stock surge contrasts with a 6.1% revenue decline over the last twelve months.
The company reported an operating margin of 1.4%.
Analysis suggests a potential disconnect between the recent stock performance and underlying company fundamentals.