The FTSE 100 index, which slumped more than 2pc on Monday, rose for the second consecutive session and added 0.3pc.
Financial stocks provided the biggest boost, supported by results of Spain's Santander.
The FTSE 250 climbed 0.2pc on Wednesday.
However, Avast underperformed with a 7pc drop, bringing its losses for the week to nearly 20pc. The cybersecurity company denied media reports and assured users that no personally identifiable information had been sold to a third party.
Both British benchmark indexes have shed more than 2pc since last week, when news of the coronavirus flare-up first emerged. Dealers are still mulling over how the outbreak will affect the global economy.
"Markets will be yearning for signs that the outbreak is stabilising," FXTM analyst Han Tan said.
"Historically, global markets tend to rebound after such outbreaks, provided that the toll exerted on the global economy is not too damaging," FXTM said, but warned that a meaningful recovery in equities could be months away.
Traders are also looking ahead to a U.S. Federal Reserve policy meeting, in which the bank is likely to leave interest rates unchanged, but may address future headwinds due to the virus outbreak.
"The emergence of the coronavirus in China will warrant a degree of caution in the outlook from the Fed, whilst there is little upward pressure on prices to suggest a shift in the FOMC's stance," Markets.com analyst Neil Wilson said.
McCarthy & Stone Plc slid 5pc as its biggest shareholder plans to slash its stake in the midcap retirement homebuilder.
Small-cap Pendragon Plc lost 4.5pc after the car dealership chain warned annual profit would be around the bottom end of its expectations.