Rows of digits scrolling along the bottom of the frame, drifting at different speeds.
The digits are the blocky bank-cheque typeface, stored as a handful of bytes each. A pixel looks up the right row of the right character and tests a single bit to find out whether it is inside a stroke or outside it.
Nothing about the ticker is stored. Which digit shows up in a given slot is worked out by scrambling the slot's position number and taking the remainder, which means an endlessly long row of digits exists without anything holding it in memory. Scroll back far enough and you find the same digits again, because the same slot number gives the same answer. Each row scrambles its own speed too, so they slide out of step with one another.
The glyphs can only brighten what is behind them, and a second lookup slightly offset draws a shadow that only darkens.