The party said the picket would highlight "the need to defend our national sovereignty and sound financial institutions against corporate capture by parasitic and corrupt networks".
The SACP will also call for the Post Bank to be strengthened to enable it to take over the payment of social welfare grants, the party's Gauteng secretary, Jacob Mamabolo, said.
"Included in that will be defending the Post Bank as a public institution without the encroaching interests of so-called private equity partners, merely intended to loot social grants."
The party said the planned protest would highlight the need to defend South Africa against "being reduced to a neo-colonial playground of capitalist interests such us the Guptas, Ruperts, Allan Grey and Oppenheimers".
The picket has been scheduled for 10am. An alliance partner of the ANC, the SACP has become outspokenly critical of President Jacob Zuma and slammed his firing of former finance minister Pravin Gordhan.