BULD is passively managed to hold globally-listed stocks and depositary receipts of companies enabling the Fourth Industrial Revolution, particularly robotics and 3D printing. The index includes firms that derive at least 50% revenue from (i) robotics & manufacturing automation equipment, (ii) computer aided design (CAD) software, or (iii) 3D printing centers, hardware, software, and materials. The index selects at least 25 securities in the first sub-industry and at least 10 each in the other two sub-industries. The resulting portfolio is weighted in tiers, with robotics & manufacturing automation allocated 50% of the portfolio weight, while CAD and 3D printing are each given 25%. Securities are weighted by market capitalization within each tier, subject to an 8% single security capping. The aggregate weight of constituents with at least 5% weight is capped at 50%. The index is reconstituted and rebalanced semi-annually