2017 was another year filled with growth and major milestones for WealthForge. More than $200 million in alternative investment transactions were completed by sponsors and investors on our platform, nearly double our transaction volume from 2016. This major growth helped us surpass $500 million in historically transacted volume early in 2018.
Throughout the year, almost 2,500 investments were made into the 119 offerings that were completed on our platform. Those successfully funded offerings were contributed by 38 valued client sponsor relationships utilizing our platform for efficient and compliance services. We were excited to see that the average investment size per investor grew 74% this year to more than $82 thousand and the average offering size climbed almost 50% year over year to $17 million.
As an example of the scale and versatility of our platform, last year we accepted our largest investment to date of nearly $2 million, as well as our smallest investment of under $100. Our largest completed offering was a private capital raise to fund an industrial real estate acquisition for $10 million and the smallest was $100 thousand for a litigation finance opportunity.
We were proud to bring 137 unique investment opportunities to market for over $2 billion in total investable volume. Through our vetted offerings, we were able to provide our advisor clients with even more opportunities to access alternative investments with the potential for attractive risk adjusted returns.
Regulation D (Reg D) offerings grew from $1.3 trillion in 2016 to $1.7 trillion in 2017. IPOs, which had slumped a year ago in 2016 were able to rebound, doubling in volume, but still remaining small in comparison to Reg D.
This past year saw the emergence of a new type of capital raising with the introduction of initial coin offerings (ICO) based on blockchain technology. While this new tech is undoubtedly transformative, at this point it continues to be a risky bet, with little in the way of investor protections or regulatory oversight, as well as a question of whether or not ICOs should even be considered securities. Nevertheless, sponsors and investors alike latched onto the idea, making ICOs a $4 billion market.
In addition to growth in Reg D and the introduction of ICO's, we continue to see expansion in Regulation A (Reg A+) and Regulation Crowdfunding (Reg CF) offerings. Reg A+, which provides companies a less expensive alternative to an IPO, saw modest growth. However, at WealthForge we are excited by the prospects of the recently updated regulation. In 2017, we successfully launched the first Reg A+ offering hosted on the WealthForge platform and hope to see continued growth in the space. Reg CF's contribution to capital markets continues to be muted due to the $1.07 million capital raising cap imposed on issuers.
2017 was a successful year for the WealthForge Network, a platform where pre-vetted offerings are showcased to our network of financial professionals and investment advisors. The successes of our network culminated at the end of the year in the following example when we saw great participation from advisors committing $9 million of client capital into a unique litigation finance fund. We continue to see increasing advisor interest to allocate to private placements, such as those on our platform.
Scroll down to view our 2017 Year In Review Infographic.