How do I transfer US Securities to IB from another broker?

Overview: 

Broker to broker transfers for US securities are conducted via a process known as the Automated Customer Account Transfer Service (ACATS).  This process generally takes between 4 to 8 business days to complete in order to accommodate the verification of the transferring account and positions. The request is always initiated by the receiving broker.  Please note that brokers generally freeze the account during this period to ensure an accurate snapshot of assets to transfer and may restrict the transfer of option positions during the week prior to expiration.

FAQS 

What does the ACATS system enable my broker to do?
The NSCC's ACATS system enables your broker to enter, review, and settle account transfers in a fully automated system.
How long does an ACATS usually take?
Under normal circumstances, an ACATS should take between four to eight business days. With some circumstances, such as an attempt to transfer unsettled funds, positions that are not paid in full, or restricted stock shares, this process could take longer.
Should I wait for my IB account to be approved before electing to fund it via ACATS?
No. In order for your application to be considered for approval, you must specify a funding election.  Note, however, that IB will not initiate your ACATS reqquest until such time as your account has been approved.
How do I initiate an account transfer that IB will receive?
The ACATS feature is available under Account Management. Choose the Funds Management and then Position Transfers menu options. After selecting the ACATS - US Broker Transfer method, you will be prompted to specify whether the transfer is full or partial, the delvering broker and, if partial, the positions to be transferred.
What if my current brokerage firm is not listed on the delivering firm dropdown menu?
The dropdown menu is a listing of Clearing Firms that are participants in the ACATS program. Not all firms are self-clearing. If you do not find your firm on the list, please contact one of their representatives to identify their clearing firm.
What products can I transfer?
Interactive Brokers accepts only products that are available for trading. Certain Fixed Income issues, Mutual Funds and Limited Partnership units are not eligible to be held in your Interactive Brokers account.
 

Can I transfer a Traditional IRA to a Roth IRA?
No. IRAs may only be transferred to the same type of IRA (i.e. Traditional to Traditional, Roth to Roth, etc.).  Also note that IRAs cannot contain any margin loans, short positions, or equity option positions.