It’s definitely a tenant’s market now. The supply of tenant’s in the market is inversely proportional to the supply of houses in the market.

The Urban Redevelopment Authority (URA) released the real estate statistics for 4th Quarter 2014.1 on 23rd January 2015 in it’s website wherein one can see that,

Rentals of private residential properties fell by 1.0% in 4th Quarter 2014, higher than the 0.8% decline in 3rd Quarter 2014 (see Annexes A-3 & A-4). 
For the year 2014 as a whole, rentals of private residential properties fell by 3.0%, compared to the 0.9% increase in 2013.

Rental Index of residential properties

Based on expected completion dates reported by developers, 24,796 units (including EC’s will be completed in 2015. 
Another 25,717 units (including EC’s) are expected to be completed in 2016.
In comparison, 23,298 units (including EC’s) were completed in 2014.
These figures show that there is going to be an additional influx of vacant units in the next 2 years from now.
This is going to add to the units already available for rent in the market.

The stock of completed private residential units (excluding EC’s) increased by 6,304 units in 4th Quarter 2014.
The vacancy rate of completed private residential units (excluding EC’s) increased to 7.8% at the end of 4th Quarter 2014, from 7.1% at the end of 3rd Quarter 2014.
These figures indicate that Projects that have TOP already have added to the stock of supply of new units, many of which maybe available for rent in the market. 

“In fact, during the Lehman crisis in Q4 2008, the vacancy rate was at 6.1 percent, which means the current percentage has increased quietly to a higher rate than what was during the 2008 Economic crisis.
But naturally, this increase is mainly attributed to the cooling measures introduced over the years and the global uncertainty.
Potential investors are now taking a wait-and-watch approach.
Adding to this is the crude oil crisis which has affected jobs in this industry leading to lay-offs.
World economic growth in 2014 was weak and is still recovering at a slow pace. Economic growth around the world is uneven.
In Singapore, there have been lay offs in a few sectors and there is a rise in expatriates not seeing employment contract terms being renewed upon expiry, leading to a growth in vacant stock in houses.  
There isn’t a huge influx of expatriates coming into Singapore, since the Government adopted policies to encourage the Citizens and residents to get priorities with regards to jobs and is stiff with granting work permits and new employment passes unless the skill is not available locally and is absolutely required by a company.  This again is a factor that contributes to vacant stock in houses.
Last but not the least the cooling measures taken by the Government have now started to show it’s effect.
Foreigners are finding Singapore as a less attractive option for employment compared to other countries now. All this definitely leads to vacant stock in houses.

The market is already seeing a decline in the number of transactions in the higher echelons of the market, so the prospect of any decline in the number of empty units looks remote.

All this by far definitely indicates that it’s a tenant’s market and going to be so for a while to come.