is weird to me because it's patently not true in the vast majority of markets that even a large company would be "a drop in the ocean" compared to the remaining market. A handful of companies would be expected to pretty quickly own more collectively than their thousands of competitors, so one of those companies going "rogue" or a few of them forming a trust would most certainly not be "a drop in the ocean."
In Germany, for example, out of every 1,000 industrial enterprises, large enterprises, i.e., those employing more than 50 workers, numbered three in 1882, six in 1895 and nine in 1907; and out of every 100 workers employed, this group of enterprises employed 22, 30 and 37, respectively. Concentration of production, however, is much more intense than the concentration of workers, since labour in the large enterprises is much more productive. This is shown by the figures on steam-engines and electric motors. If we take what in Germany is called industry in the broad sense of the term, that is, including commerce, transport, etc., we get the following picture. Large-scale enterprises, 30,588 out of a total of 3,265,623, that is to say, 0.9 per cent. These enterprises employ 5,700,000 workers out of a total of 14,400,000, i.e., 39.4 per cent; they use 6,600,000 steam horse power out of a total of 8,800,000, i.e., 75.3 per cent, and 1,200,000 kilowatts of electricity out of a total of 1,500,000, i.e., 77.2 per cent.
Less than one-hundredth of the total number of enterprises utilise more than three-fourths of the total amount of steam and electric power! Two million nine hundred and seventy thousand small enterprises (employing up to five workers), constituting 91 per cent of the total, utilise only 7 per cent of the total amount of steam and electric power! Tens of thousands of huge enterprises are everything; millions of small ones are nothing.
Lenin used publically-available statistics to demonstrate this in Imperialism: The Highest Stage of Capitalism, and wealth has only gotten more concentrated since then. Here's an example from that text, for those who are unfamiliar: