Wealth, or capital, tends to be represented in the earliest Holmes stories in the reassuringly familiar form of specie (coins and notes), or precious stones or metals. The Agra treasure in The Sign of Four, the French gold in ‘The Red-Headed League’, the Australian gold mines of ‘The Boscombe Valley Mystery’ (1891) and the American gold mine of Hatty Moran's father in ‘The Noble Bachelor’, the 421 pennies and 270 half-pennies in ‘The Man with the Twisted Lip’ (1891), the blue carbuncle, the counterfeit half-crowns in ‘The Engineer's Thumb’, the fifty thousand pounds in notes loaned to the illustrious client in exchange for a priceless piece of jewellery in ‘The Adventure of the Beryl Coronet’ (1892) – all are examples of the most solid forms of capital. Even the opium den in ‘The Man with the Twisted Lip’ is named ‘The Bar of Gold’. Several of these stories belong to a tradition of narratives, stretching back to Chaucer's tale of the Pardoner but including such favourites of Doyle's as Collins's The Moonstone and Edgar Allan Poe's ‘The Gold Bug’ (1843), in which great wealth in material, tactile form motivates characters to perform extraordinary feats.

The stories in The Memoirs of Sherlock Holmes (1893), The Hound of the Baskervilles (1902) and The Return of Sherlock Holmes (1905) reveal a striking and important change. Specie and precious objects become less prominent, and their function is replaced by a form of capital that is insubstantial, abstract and, in some ways, even theoretical. Securities, which include government stocks as well as shares in private companies, are the preferred form of capital in the plots of several of these later stories, and appear with surprising frequency as incidental details. In The Hound of the Baskervilles, for instance, we are told that Sir Charles Baskerville made ‘large sums of money in South African speculation’, after which ‘he realised his gains and returned to England’, where he invested his profits in ‘those schemes of reconstruction and improvement’ at Baskerville Hall ‘which have been interrupted by his death’ (15). This detail may, in fact, be more than merely incidental, as it provides a pecuniary motive for Stapleton, a disguised Baskerville, to kill the man he knows to be his uncle and to plot the death of his cousin, in addition to all the other benefits of becoming the squire of Baskerville Hall.