Certain statements made during this conference call may be deemed forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Although Health Care REIT believes results projected in any forward-looking statements are based on reasonable assumptions, the company can give no assurance that its projected results will be attained. Factors and risks that could cause actual results to differ materially from those in the forward-looking statements are detailed in the news release and from time to time in the company's filings with the SEC.
I will now turn the call over to George Chapman, Chairman and CEO and President of Health Care REIT, for his opening remarks. George?
George L. Chapman
Thanks, Jeff. I'm pleased to report another strong quarter for our company and its shareholders. Our relationship investment strategy is hitting on all cylinders, driving $1.1 billion of investments for the second quarter and $1.9 billion year-to-date. And the pipeline remains quite strong. Of the $1.1 billion of new Q2 investments, over 50% of them were with existing partners. As we look over the last 3 quarters, we closed over $2 billion of relationship investments that comprised approximately 2/3 of the total. Importantly, the portfolio generated second quarter year-over-year same-store cash NOI growth of 4.2%. This was led by a strong 7.4% growth from our senior housing operating portfolio. And notably, every category posted at least a 3% NOI growth.During the last 5 years, we have taken advantage of unprecedented opportunities to transform our portfolio into the most diversified, highest-quality, lowest-risk portfolio in the sector. And in the second quarter, our portfolio exceeded 1,000 properties for the first time. And we have attracted the industry's finest operators and health systems, largely as a result of our reputation as a value-added partner. Importantly, due to our relationship investment program, we have the most predictable, consistent investment pipeline in the sector.