S-form

The s-form^[1] is the English language phenomenon of suffixing -'s or -s to business names where there is not one present in writing, predominantly in colloquial speech.^[2] This is particularly common with the names of supermarkets. For example Tesco could be converted to Tesco's in speech, Safeway to Safeways, Wal-Mart to Wal-Mart's, etc.

Foreigners come across this form especially as concerns manufacturers; mere retailers like the above examples remain customers' and employees' conversation. For example, the firm Short Brothers (of Belfast) built the aircraft called the Short Sunderland, but the firm is colloquially given as Shorts.

Causes

It is most likely that the s-form is an overgeneralisation of the possessive suffix common in business names.^[3]

References

Look up -s in Wiktionary, the free dictionary.