The TIC Form SLT collects monthly data on the market value of long-term cross-border securities holdings by country, type of foreign holder (official or private), and type of security. We estimate transactions as well as valuation change that is, the monthly change in the market value of the securities arising from price or exchange rate changes. Since the valuation change estimates are based on the country of issuer, the price indexes used for U.S. securities are the same for all holder countries. Over the ten years that TIC SLT data have been collected, this method has yielded estimated transactions more consistent with positions reported in the TIC SLT, with the findings of the annual security-level survey data, and with our expectations based on other information, such as market commentary or patterns observed across time.This dataset includes position, estimated transaction, and estimated valuation change data for counterparty countries that (1) have published TIC SLT position data and (2) have significant reported positions. This set of countries accounts for 95 to 99 percent of all long-term cross-border securities holdings.