The Minion toy on her desk turns out to be significant. Ben Moshinsky/Business Insider Technology in global investment banking has gone from a necessary cost to a possible savior.

The banks that get their technology strategy right will stay profitable at a time when sluggish global growth, low interest rates, and ever-developing regulations are hitting the bottom line. Those that don't, won't.

Goldman Sachs is aiming to be in the former camp. It employs about 9,000 people in its tech division globally, roughly 25% of its total staff.

We had the opportunity to follow two of them around for the day in London: Samira, a developer working on trading applications for the foreign-exchange desk, and Ria, who works in cybersecurity-threat detection.

Here's what their days are like: