In a study of 2400 sales teams, the Sales Executive Council correlated a 17 percent improvement in the average level of quota attainment between teams receiving 2 or fewer hours of coaching per month and those teams receiving 3 or more hours per month. Here are the results of that specific analysis:
In the same study, the SEC looked at how the responding firms rated their sales managers on ten key management competencies. Ironically, coaching, the skill that seemed to have so promising an impact on quota performance, rated dead last in the reporting of key competencies:
Quantified Benefits of Coaching to a Business
Korn/Ferry International reviewed the results of three ROI studies in a presentation to the 2008 International Coach Federation Global Conference. In three studies, they found quantifiable returns ranging from almost six to almost eight times the investment made in the coaching programs.
Here are the results of the three studies cited:

Other Benefits of Coaching
In 2001, Manchester, Inc., an executive coaching firm, released a study of 100 executives, mostly from Fortune 1,000 companies, which ranked how often respondents mentioned benefits to the company and benefits to the recipient of the coaching. The results of those queries are presented below.
Benefits to the Company:
The three most often reported benefits reported by the company included increased productivity (mentioned in 53% of the responses), improved quality (48%) and organizational strength (48%)
Here are the complete results:
Benefits to executives receiving the coaching:
In the same study, Manchester, Inc. reported that the most commonly reported benefits to the individual executives receiving the coaching included improved working relationships with their direct reports (mentioned in 77% of the responses), improved working relationship with the immediate supervisor of the surveyed executive (71%), and improved teamwork (67%)
Complete results:
