Robot home builder Fastbrick has lost its much-hyped Caterpillar partnership and the machinery giant is selling out.

The reason given was that Fastbrick (ASX:FBR) did not reflect Caterpillar’s “strategic priorities”.

The company’s stock dropped 24 per cent to 12.5c, on Wednesday morning so far.

The MoU was signed in July last year to see if Fastbrick’s robotic bricklaying technology could work for Caterpillar’s construction customers.

Fastbrick said it “demonstrated global scalability” of its technology.

It included a $US2m ($2.6m) investment by Caterpillar subsidiary Wisconsin Holdings into Fastbrick, with an option to invest another $US8m.

Caterpillar never took up that option.

Fastbrick spokesman Kiel Chivers told Stockhead the MoU signed with Saudi Arabia in August last year is still on track.

Fastbricks shares over the last 12 months.

The MoU was extended in June this year with another option to invest $US10m, “in order to allow FBR additional time to demonstrate its technology to Caterpillar in line with the original intentions of the MOU and FBR’s current development schedule”.

Fastbrick said the breakup was mutual.

Caterpillar will sell its 2.13 per cent stake “in due course”.

“Due to emerging strategic imperatives, we have agreed to discontinue our Memorandum of Understanding with Caterpillar. We acknowledge Caterpillar’s support to date and despite our strategic divergence we will continue to consider opportunities where we can work together in the future,” said Fastbrick CEO Mike Pivac in a statement.

Fastbrick also admitted to investors that its first complete home build was conducted indoors — the original plan was to have the first outdoor build completed by the end of 2018.

Mr Chivers said they anticipate that to now happen in the first three months of 2019.